Co-reporter:Hong-Hong Fan, Huan-Huan Li, Ke-Cheng Huang, Chao-Ying Fan, Xiao-Ying Zhang, Xing-Long Wu, and Jing-Ping Zhang
ACS Applied Materials & Interfaces March 29, 2017 Volume 9(Issue 12) pp:10708-10708
Publication Date(Web):March 6, 2017
DOI:10.1021/acsami.7b00578
Marcasite (m-FeS2) exhibits higher electronic conductivity than that of pyrite (p-FeS2) because of its lower semiconducting gap (0.4 vs 0.7 eV). Meanwhile, as demonstrates stronger Fe–S bonds and less S–S interactions, the m-FeS2 seems to be a better choice for electrode materials compared to p-FeS2. However, the m-FeS2 has been seldom studied due to its sophisticated synthetic methods until now. Herein, a hierarchical m-FeS2 and carbon nanofibers composite (m-FeS2/CNFs) with grape-cluster structure was designed and successfully prepared by a straightforward hydrothermal method. When evaluated as an electrode material for lithium ion batteries, the m-FeS2/CNFs exhibited superior lithium storage properties with a high reversible capacity of 1399.5 mAh g–1 after 100 cycles at 100 mA g–1 and good rate capability of 782.2 mAh g–1 up to 10 A g–1. The Li-storage mechanism for the lithiation/delithiation processes of m-FeS2/CNFs was systematically investigated by ex situ powder X-ray diffraction patterns and scanning electron microscopy. Interestingly, the hierarchical m-FeS2 microspheres assembled by small FeS2 nanoparticles in the m-FeS2/CNFs composite converted into a mimosa with leaves open shape during Li+ insertion process and vice versa. Accordingly, a “CNFs accelerated decrystallization–recrystallization” mechanism was proposed to explain such morphology variations and the decent electrochemical performance of m-FeS2/CNFs.Keywords: anode materials; carbon nanofibers; FeS2; lithium ion batteries; marcasite;
Co-reporter:Lihan Zhu;Haiyan Yuan;Jingping Zhang
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 43) pp:9127-9138
Publication Date(Web):2017/11/07
DOI:10.1039/C7OB02081C
A comprehensive density functional theory investigation was employed to disclose the effect of reaction conditions on the mechanism and effective anion relay sequence of a NaH promoted non-Brook rearrangement of benzaldehyde and 1-cinnamoylcyclopropanecarboxamides. Two main mechanisms were explored under four different reaction conditions: Na+-assisted and nH2O-Na+, 2H2O-DMSO-Na+, and Na+-DMSO co-assisted, and the difference relies on the reaction sequence between the concerted ring-opening and recyclization and electrophilic addition. Being different from previous reports, a cooperative participation of water, solvent DMSO and counterion Na+ is revealed in the preferential mechanism. The preferred scenario undergoes five major steps: deprotonation, aza-Michael addition, electrophilic addition, NaOH elimination and a concerted ring-opening and recyclization step. The rate-determining step is the concerted ring-opening and recyclization process with an energy barrier of 30.2 kcal mol−1. We found that the effective anion relay of a non-Brook rearrangement order is N → Cα → O rather than the previously proposed aza-oxy-carbanion. Meanwhile, a mixed type of ARC chemistry through a novel non-Brook rearrangement was disclosed. Moreover, the non-covalent interactions between substrate and reactant extensively affect the anion relay process by hydrogen-bonding (O–H⋯O and C–H⋯O) and electrostatic (Na+⋯O) interactions. Thus, our results provide insightful clues to the mechanism of the reaction condition catalyzed non-Brook rearrangement reaction.
Co-reporter:Huan-Huan Li, Lei Zhou, Lin-Lin Zhang, Chao-Ying Fan, Hong-Hong Fan, Xing-Long WuHai-Zhu Sun, Jing-Ping Zhang
ACS Energy Letters - New in 2016 2017 Volume 2(Issue 1) pp:
Publication Date(Web):December 1, 2016
DOI:10.1021/acsenergylett.6b00564
Herein, we develop a Co3O4-based anode material with a hierarchical structure similar to that of a lotus pod, where single yolk–shell-structured Co3O4@Co3O4 nanospheres are well embedded in a nitrogen-doped carbon (N–C) conductive framework (Co3O4@Co3O4/N–C). This distinctive architecture contains multiple advantages of both the yolk–shell structure and conductive N–C framework to improve the Li ion storage performance. Especially, the doping of the N atom in N–C increases the interaction between the carbon and adsorbents, which is confirmed by the theoretical calculations in this work, making the carbon framework much more electrochemically active. As a result, the Co3O4@Co3O4/N–C exhibits fast surface-controlled kinetics, which corroborate the high counterion mobility and the ultrafast electron-transfer kinetics of the electrode. Due to these synergetic effects, desired capacity stability (1169.6 mAh g–1 at 200 mA g–1 after 100 cycles) and superior rate performance (633.4 mAh g–1 at 10 A g–1) have been realized in this Co3O4@Co3O4/N–C electrode.
Co-reporter:Chao-Ying Fan;Si-Yu Liu;Huan-Huan Li;Yan-Hong Shi;Han-Chi Wang;Hai-Feng Wang;Hai-Zhu Sun;Xing-Long Wu
Journal of Materials Chemistry A 2017 vol. 5(Issue 22) pp:11255-11262
Publication Date(Web):2017/06/06
DOI:10.1039/C7TA02231J
Although the composite of metal oxide and porous carbon has been confirmed as an effective material to chemically adsorb polysulfides, the low conductivity of the metal oxide results in the need for extra pathways for the diffusion of polysulfides from adsorption sites to redox-active sites. This process results in sluggish reaction kinetics and escaped polysulfides. In this work, a Gerber tree-like interlayer with multiple components was designed to fully mediate the electrochemical conversion of Li–S batteries and shorten the diffusion distance of polysulfides in the composite. The branches of the interlayer contained TiO2 and Co3O4 nanocrystals embedded into N-doped porous carbon, while the fruit was catalytic metal cobalt. The two co-existing chemical adsorbents ensure the restriction of polysulfides through S–Ti–O bonding and Lewis acid–base interaction. Moreover, the metal Co catalyzes the transformation of adsorbed polysulfides into low-order ones, which largely shortens the diffusion pathway, improving the reaction kinetics and preventing the migration of polysulfides. The cell with the interlayer exhibited outstanding electrochemical performance. After 100 cycles, a reversible capacity of 968 mA h g−1 was maintained at 0.1C with a stable capacity retention of 85%. Even at the current rate of 1C, the cell delivered a capacity of 684.5 mA h g−1 after 300 cycles.
Co-reporter:Hai-Feng Wang, Chao-Ying Fan, Xiao-Ying Li, Xing-Long Wu, Huan-Huan Li, Hai-Zhu Sun, Hai-Ming Xie, Jing-Ping Zhang, Cui-Yan Tong
Electrochimica Acta 2017 Volume 244(Volume 244) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.electacta.2017.05.090
Lithium sulfur (Li-S) batteries possess high theoretical specific capacity (1675 mAh g−1) and energy density (2567 Wh kg−1), but are plagued by their poor rate performance. The discovery of new carbon sources, design of novel porous carbon structures, and effective hetero-atom doping of the sulfur matrix are key to overcome this dilemma. In this paper, a boron-doped porous carbon material with a termite nest shape (TNPBC) was obtained from a new carbon source, polyaspartic acid, and borax. Importantly, the doping, activation, and pyrolysis were integrated into one step through a low cost and simple methodology. The borax was essential to formation of a high surface porous architecture and provided boron dopants, which, combined with polyaspartic acid, achieves co-doping (B and N) carbon materials with special porous structures. The simultaneous pore-formation and doping leave an abundance of hetero-atoms exposed on the surface of pores, which enhances the electrostatic interactions between the hetero-atoms and the charged species in the batteries. As a result, the S/TNPBC cathode maintains a stable capacity of 703 mAh g−1 with an excellent Coulombic efficiency of 101.3% after 120 cycles at 0.1C. Moreover, it exhibits an excellent rate capability with an initial capacity of 650 mAh g−1 at 0.5C and sustains a capacity of 500 mAh g−1 after 100 cycles. Furthermore, when TNPBC is used as the anode in a sodium ion battery, an excellent rate capability is achieved. The specific charge capacity is three times greater than without boron doping at 500 mA g−1. Due to the simple fabrication process and desirable properties of this novel architecture, TNPBC provides a new strategy for enhancing the performance of commercial energy storage devices.A novel kind of porous boron-doped carbon (TNPBC) with a termite nest structure was synthesized by combining doping, activation, and pyrolysis into one step. Using the synthesized material as a sulfur reservoir, TNPBC effectively relieved the “shuttle effect” commonly found in Li-S electrodes and achieved a decent rate performance in Li-S and sodium ion batteries.Download high-res image (181KB)Download full-size image
Co-reporter:Jing Wang, Jing Lu, Jingping Zhang
Dyes and Pigments 2017 Volume 143(Volume 143) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.dyepig.2017.03.064
•Thermally activated delayed fluorescence materials emitting wavelengths are tuned.•Excited state characteristics are confirmed via hole-electron distribution analysis.•Diphenylsulphone based molecules with small singlet-triplet energy gaps are designed.A series of designed diphenylsulphone based thermally activated delayed fluorescent materials have been investigated using quantum chemical approach. We focused on the variation in electronic and optical properties as different substituents being introduced to the parent molecule. The calculated results show that the broad range emission wavelengths (352–731 nm) can be tuned via either H/R substitution on the donor/acceptor moieties or “CH”/N substitution on the donor moieties. The emission wavelengths are significantly bathochromic-shifted (15–252 nm) by introduction of electron-accepting groups (CN) on the acceptor fragment or electron-donating groups (CH3) on the donor fragments. While, “CH”/N substitution on the donor fragment results in hypochromatic shifts (10–127 nm). On basis of the hole-electron distributions analysis, the locally excited triplet states are close to or higher than the triplet intramolecular charge transfer state for most of the investigated molecules. Furthermore, the calculated singlet-triplet energy gap values of the designed four red emission molecules (0.007–0.014 eV), two green ones (0.010–0.013 eV) and a blue one (0.058 eV) are relatively small, indicating that these investigated derivatives are excellent thermally activated delayed fluorescent candidates. Our theoretical studies provide hints for the design of efficient broad emission thermally activated delayed fluorescent materials in the future.
Co-reporter:Xiaoying Zhang, Xiaolei Li, Jingping Zhang
Inorganic Chemistry Communications 2017 Volume 84(Volume 84) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.inoche.2017.07.022
•Two new 3D open-framework metal phosphites have been synthesized under solvothermal conditions.•Compounds 1 and 2 show left/right-handed helical channels and 16-membered ring channels.•Complex 2 represents the first monometallic four-coordinate manganese phosphite.•These two phosphite complexes 1 and 2 display antiferromagnetic behavior.Two new 3D open-framework metal phosphites [(CH3)2NH2]2Co3(HPO3)4 (1) and [(CH3)2NH2]2Mn3(HPO3)4 (2) have been solvothermally synthesized. Single-crystal X-ray diffraction analysis shows that complexes 1 and 2 are isomorphic structures, with left/right-handed helical channels and 16-membered ring channels. Complex 2 represents the first monometallic four-coordinate manganese phosphite. These two phosphite complexes 1 and 2 display antiferromagnetic behavior.We report two novel phosphites [(CH3)2NH2]2M3(HPO3)4 (M = Co(1), Mn(2)) with extra-large 16-membered ring channels and left/right-handed helical channels. Complex 2 represents the first monometallic four-coordinate manganese phosphite. Magnetic studies showed that there exist weak antiferromagnetic interactions between M(II) ions in 1 and 2.Download high-res image (266KB)Download full-size image
Co-reporter:Lin Zhang;Pin Xiao;Xiaoxue Guan;Zhouliang Huang;Jingping Zhang;Xihe Bi
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 7) pp:1580-1583
Publication Date(Web):2017/02/15
DOI:10.1039/C7OB00019G
The radical coupling of isocyanides and alcohols/phenols promoted by silver in the presence of water is reported for the first time, which led to the formation of diverse carbamates. In contrast to the well-known 1,1-addition to form imidoyl radicals, a novel reaction mechanism, involving sequential hydration of isocyanides and coupling with alkoxyl/phenoxyl radicals, is disclosed by combining experimental and theoretical studies.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 6) pp:2055-2059
Publication Date(Web):07 Jan 2016
DOI:10.1039/C5TA08779A
A dissolution–recrystallization method was developed to prepare flexible paper electrodes constructed of Zn2GeO4 nanofibers anchored with amorphous carbon (ZGO/C-P) for high energy and power Li-ion batteries. The ZGO/C-P exhibits superior long-term cycle stability (up to 2000 cycles at 1 A g−1) and excellent rate capability.
Co-reporter:Huan-Huan Li, Zi-Yao Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 21) pp:8242-8248
Publication Date(Web):18 Apr 2016
DOI:10.1039/C6TA02417C
In recent years, metal-organic compounds have been considered as ideal sacrificial templates to obtain transition metal oxides for electrochemical applications due to their diverse structures and tunable properties. In this work, a new kind of cobalt-based metal organic compound with a layered structure was designed and prepared, which was then transformed into ultrafine cobalt oxide (Co3O4) nanocrystallites via a facile annealing treatment. The obtained Co3O4 nanocrystallites further assembled into a hierarchical shale-like structure, donating extremely short ion diffusion pathway and rich porosity to the materials. The special structure largely alleviated the problems of Co3O4 such as inferior intrinsic electrical conductivity, poor ion transport kinetics and large volume changes during the redox reactions. When evaluated as anode materials for lithium-ion batteries, the shale-like Co3O4 (S-Co3O4) exhibited superior lithium storage properties with a high capacity of 1045.3 mA h g−1 after 100 cycles at 200 mA g−1 and good rate capabilities up to 10 A g−1. Moreover, the S-Co3O4 showed decent electrochemical performance in sodium-ion batteries due to the above-mentioned comprehensive merits (380 and 153.8 mA h g−1 at 50 and 5000 mA g−1, respectively).
Co-reporter:Chao-Ying Fan, Hai-Yan Yuan, Huan-Huan Li, Hai-Feng Wang, Wen-Liang Li, Hai-Zhu Sun, Xing-Long Wu, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 25) pp:16108-16115
Publication Date(Web):June 10, 2016
DOI:10.1021/acsami.6b04578
In this work, the lightweight and scalable organic macromolecule graphitic carbon nitride (g-C3N4) with enriched polysulfide adsorption sites of pyridinic-N was introduced to achieve the effective functionalization of separator at the molecular level. This simple method overcomes the difficulty of low doping content as well as the existence of an uncontrolled form of nitrogen heteroatom in the final product. Besides the conventional pyridinic–N-Li bond formed in the vacancies of g-C3N4, the C–S bond was interestingly observed between g-C3N4 and Li2S, which endowed g-C3N4 with an inherent adsorption capacity for polysulfides. In addition, the microsized g-C3N4 provided the coating layer with good mechanical strength to guarantee its restriction function for polysulfides during long cycling. As a result, an excellent reversible capacity of 840 mA h g–1 was retained at 0.5 C after 400 cycles for a pure sulfur electrode, much better than that of the cell with an innocent carbon-coated separator. Even at a current density of 1 C, the cell still delivered a stable capacity of 732.7 mA h g–1 after 500 cycles. Moreover, when further increasing the sulfur loading to 5 mg cm–2, an excellent specific capacity of 1134.7 mA h g–1 was acquired with the stable cycle stability, ensuring a high areal capacity of 5.11 mA h cm–2. Besides the intrinsic adsorption ability for polysulfides, g-C3N4 is nontoxic and mass produced. Therefore, a scalable separator decorated with g-C3N4 and a commercial sulfur cathode promises high energy density for the practical application of Li–S batteries.
Co-reporter:Lin-Lin Zhang, Huan-Huan Li, Yan-Hong Shi, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Hai-Zhu Sun, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 6) pp:4233
Publication Date(Web):January 27, 2016
DOI:10.1021/acsami.5b12484
In this paper, gelatin as a natural biomass was selected to successfully prepare an oxygen-enriched carbon with layered sedimentary rocks structure, which exhibited ultrahigh-rate performance and excellent cycling stability as supercapacitors. The specific capacitance reached 272.6 F g–1 at 1 A g–1 and still retained 197.0 F g–1 even at 100 A g–1 (with high capacitance retention of 72.3%). The outstanding electrochemical performance resulted from the special layered structure with large surface area (827.8 m2 g–1) and high content of oxygen (16.215 wt %), which effectively realized the synergistic effects of the electrical double-layer capacitance and pseudocapacitance. Moreover, it delivered an energy density of 25.3 Wh kg–1 even with a high power density of 34.7 kW kg–1 and ultralong cycling stability (with no capacitance decay even over 10 000 cycles at 2 A g–1) in a symmetric supercapacitor, which are highly desirable for their practical application in energy storage devices and conversion.Keywords: biomass; layered sedimentary rocks structure; oxygen-enriched; symmetric supercapacitor; ultrahigh-rate performance
Co-reporter:Huan-Huan Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Hai-Zhu Sun, Jing-Ping Zhang, and Qingyu Yan
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 46) pp:31722
Publication Date(Web):November 2, 2016
DOI:10.1021/acsami.6b11503
In this work, carbon-free, porous, and micro/nanostructural Zn2GeO4 nanofibers (p-ZGONFs) have been prepared via a dissolution-recrystallization-assisted electrospinning technology. The successful electrospinning to fabricate the uniform p-ZGONFs mainly benefits from the preparation of completely dissolved solution, which avoids the sedimentation of common Ge-containing solid-state precursors. Electrochemical tests demonstrate that the as-prepared p-ZGONFs exhibit superior Li-storage properties in terms of high initial reversible capacity of 1075.6 mA h g–1, outstanding cycling stability (no capacity decay after 130 cycles at 0.2 A g–1), and excellent high-rate capabilities (e.g., still delivering a capacity of 384.7 mA h g–1 at a very high current density of 10 A g–1) when used as anode materials for lithium ion batteries (LIBs). All these Li-storage properties are much better than those of Zn2GeO4 nanorods prepared by a hydrothermal process. The much enhanced Li-storage properties should be attributed to its distinctive structural characteristics including the carbon-free composition, plentiful pores, and macro/nanostructures. Carbon-free composition promises its high theoretical Li-storage capacity, and plentiful pores cannot only accommodate the volumetric variations during the successive lithiation/delithiation but can also serve as the electrolyte reservoirs to facilitate Li interaction with electrode materials.Keywords: anode materials; carbon-free; electrospinning; lithium ion batteries; Zn2GeO4
Co-reporter:Chao-Ying Fan, Si-Yu Liu, Huan-Huan Li, Hai-Feng Wang, Han-Chi Wang, Xing-Long Wu, Hai-Zhu Sun, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 42) pp:28689
Publication Date(Web):October 12, 2016
DOI:10.1021/acsami.6b10515
The synergistic design of cathode region was conducted to minimize the shuttle effect of polysulfides and decrease the loading of inactive components in order to acquire high-energy-density lithium–sulfur (Li–S) batteries. The well-designed cathode region presented two special characteristics: one was the intertwined nanofibers interlayer based on ultrafine TiO2 nanocrystal uniformly embedded within N-doping porous carbon; the other was the lightweight and three-dimensional current collector of fibrous cellulose paper coated by reduced graphene oxide. In consequence, the decent reversible capacity of 874.8 mA h g–1 was acquired at 0.1 C with a capacity retention of 91.83% after 100 cycles. Besides, the satisfactory capacity of 670 mA h g–1 was delivered after 300 cycles at 1 C with the small decay rate of only 0.08%. Because of higher capacity and lower loading of inactive component in cathode region, the energy density of cell increased more than five times compared with unmodified cell. Moreover, to further enhance the energy density, the high-sulfur-loading electrode was fabricated. A good areal capacity of 4.27 mA h cm–2 was retained for the cell with the active material of 4 mg cm–2 and the cycle stability was also well-maintained. In addition, due to the flexibility of interlayer and current collector, Li–S full cell (in pouch cell format) was easily curved. Therefore, the synergistic design for cathode region, which combines the flexible and mass-produced interlayer and current collector together, provides an effective access to Li–S batteries with high energy density and flexibility for practical application.Keywords: cathode region; high energy density; lightweight current collector; Li−S batteries; TiO2 interlayer
Co-reporter:Xiaoying Zhang, Bo Li, and Jingping Zhang
Inorganic Chemistry 2016 Volume 55(Issue 7) pp:3378-3383
Publication Date(Web):March 21, 2016
DOI:10.1021/acs.inorgchem.5b02785
Four helical copper complexes Cu[N(CN)2]2(Hhmp) (1), {Cu[N(CN)2]2(Hhmp)}∞ (2), (l-{Cu4[N(CN)2]2(hmp)4(CH3COO)2·CH3CN}∞ (3a), and d-{Cu4[N(CN)2]2(hmp)4(CH3COO)2·CH3CN}∞ (3b) (Hhmp = 2-(hydroxymethyl)pyridine) have been prepared toward a mimic DNA structure. By changing the solvent and supplementary ligand, the structures can be successfully tuned from quasi-double-helical (complex 1) to racemic 1D single helix (complex 2), then the right (3a)-/left (3b)-handed double helices. The topologies of 3a and 3b may be considered as a mimic of DNA, where the Cu–O bonds between the two strands replace the hydrogen-bonding interactions in DNA. Solid-state circular dichroism spectra confirmed that 3a and 3b are optically active, respectively. Magnetic measurements for 1–3 indicated all complexes to be antiferromagnetic interactions. The best fitting results to the magnetic susceptibilities were J = −0.80 cm–1, g = 2.11 for 1 and J1 = −9.22 cm–1, J2 = 3.56 cm–1, J3 = −9.49 cm–1, g = 2.27 for 3.
Co-reporter:Kang Wang, Yan-Hong Shi, Huan-Huan Li, Hai-Feng Wang, Xiao-Ying Li, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie, Jing-Ping Zhang, Jia-Wei Wang
Electrochimica Acta 2016 Volume 215() pp:267-275
Publication Date(Web):10 October 2016
DOI:10.1016/j.electacta.2016.08.085
A novel kind of MnCO3 nanoplatelets-reduced graphene oxide (RGO) composites, as an anode material in rechargeable Li-ion battery, was prepared by a simple low temperature reaction route. The graphene not only provided an avenue for the transport of Li-ion, but also buffered the volume expansion of MnCO3 nanoplatelets during charge and discharge. Compared to pure MnCO3 nanoplatelets, MnCO3-RGO composites presented the improved electrochemical performances. At a low current density of 100 mA g−1, MnCO3-RGO composites delivered a desired performance of 849.1 mAh g−1 after 200 cycles. When at a high current density of 500 mA g−1, the discharge capacity still maintained at 810.9 mAh g−1 after 700 cycles. Our experimental results suggest that this composite will be a candidate as a novel anode material for the power batteries of electric vehicles and the energy storage batteries of smart grids in the future.A novel kind of MnCO3 nanoplatelets-reduced graphene oxide (RGO) composite was prepared by a simple low temperature reaction route which presented improved rate performance.
Co-reporter:Jing Lu, Yiying Zheng, Jingping Zhang
Dyes and Pigments 2016 Volume 127() pp:189-196
Publication Date(Web):April 2016
DOI:10.1016/j.dyepig.2015.12.030
•A reverse intersystem crossing from higher triplet to singlet excited states is proposed.•The calculated emission wavelengths of these investigated molecules may exhibit long wavelength emission characters.•The charge transfer properties of these design molecules are calculated using density functional theory.A series of benzo [1,2-b:4,5-b′]dithiophene based thermally activated delayed fluorescent molecules have been designed and investigated using density functional theory and time-dependent density functional theory. The theoretical calculations showed that the designed 4, 8-positions of benzo [1,2-b:4,5-b′]dithiophene substituted molecules exhibited a mixed states, which comprised a large proportion of charge transfer components and a small part of locally excited components. The calculated emission wavelengths of the investigated molecules may exhibit long wavelength emission characters. For the designed 4, 8-positions substituted molecule with two [1,2,5]thiadiazolo[3,4-c]pyridine-7-carbonitrile electron-accepting units, which exhibited zero singlet-triplet energy gap, the predicted hole and electron mobilities are 3.43 cm2 v−1 s−1 and 0.18 cm2 v−1 s−1, respectively. Our study may provide new ideas for the design of highly efficient thermally activated delayed fluorescent candidates by realizing the full potential of both singlet and triplet excitons.Computational design of benzo [1,2-b:4,5-b′]dithiophene based thermally activated delayed fluorescent molecules by realizing the full potential of both singlet and triplet excitons.
Co-reporter:Shamsa Bibi and Jingping Zhang
New Journal of Chemistry 2016 vol. 40(Issue 4) pp:3693-3704
Publication Date(Web):19 Feb 2016
DOI:10.1039/C5NJ02412A
We have designed three dimensional conjugated three- and four-armed molecules for organic solar cells, featuring a bithiophene donor (DF) fragment connected to a pyridine-thiadiazole acceptor fragment (AF) via an ethyne π-spacer (Ps) as the arms, which are linked to different central core atoms (N, B, C and Si atoms) based on two topologies, “core-D–π–A” (molecules are named N3-Mol, B3-Mol, Si4-Mol and C4-Mol) and “core-A–π–D” (molecules are named N3-RMol, B3-RMol, Si4-RMol and C4-RMol). A combination of density functional theory (DFT) and time-dependent-DFT (TD-DFT) approaches is applied to understand the effect of different central cores on the optical, electronic and charge transport properties of the two topologies. The “core-A–π–D” type molecules display smaller Eg values than those of the “core-D–π–A” type molecules. Therefore, the “core-A–π–D” type molecules show a significant red shift in λmax compared to the “core-D–π–A” type molecules. The molecules C4-RMol, Si4-RMol, B3-RMol and N3-RMol show red shifts of 59, 14, 28 and 39 nm in λmax as compared to C4-Mol, Si4-Mol, B3-Mol and N3-Mol, respectively. Three-armed N3-Mol and N3-RMol display the largest λmax of the designed molecules. Interestingly, B3-RMol and C4-RMol show more or less same λmax values. However, B and Si cores also show more intense absorption bands than N and C cores, respectively. Both the reorganization energy and mobility results reveal that the four-armed molecules show higher charge transport rates than the three-armed molecules because of their better dimensionality. N3-RMol exhibits μe and μh mobilities of up to 2.8 × 10−2 cm2 V−1 s−1 and 3.3 × 10−2 cm2 V−1 s−1 respectively while C4-RMol shows higher μe and μh mobilities of up to 0.163 cm2 V−1 s−1 and 4.14 × 10−2 cm2 V−1 s−1 respectively in the crystalline state, which have been predicted using the P21/c space group. Thus, the comparative analysis of the designed molecules reveals that the “core-A–π–D” topology with the substitution of N and C cores results in molecules which exhibit a narrow Eg, broad and intense absorptions and an anisotropic high charge carrier mobility in the crystalline phase, which is associated with low reorganization energies for organic solar cells.
Co-reporter:Fang Wan;Yu-Han Li;Dai-Huo Liu;Jin-Zhi Guo; Hai-Zhu Sun; Jing-Ping Zhang; Xing-Long Wu
Chemistry - A European Journal 2016 Volume 22( Issue 24) pp:8152-8157
Publication Date(Web):
DOI:10.1002/chem.201600660
Abstract
Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na+ and e− transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li+, Na+, K+)-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g−1 after 600 cycles at 1 A g−1) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na−O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions.
Co-reporter:Yujia Pang
The Journal of Physical Chemistry C 2016 Volume 120(Issue 8) pp:4329-4336
Publication Date(Web):February 9, 2016
DOI:10.1021/acs.jpcc.5b10284
On the basis of the recently synthesized cyclo-1,4-phenylene-2′,5′-thienylenes ([n]CPTs) (Ito et al. Angew. Chem. Int. Ed.2015, 54, 159–163), a set of nanoporous molecular crystals were designed, and the adsorption properties were investigated by means of Grand canonical Monte Carlo simulations, in which the force field for describing the interactions between molecules was derived from the dispersion-corrected double-hybrid density functional theory. A sufficient number of accurate reference data is used for producing the force field, which confirms the accuracy of our simulations. The results suggest that the tunable pore size of CPTs makes them suitable for practical applications of H2 or CO storage, and very interestingly, under proper conditions, they are potential candidates for purification of H2. The multiscale simulations provide new insight into the application of the novel thiophene-based CPTs in gas storage and purification.
Co-reporter:Haiyan Yuan, Yiying Zheng, and Jingping Zhang
The Journal of Organic Chemistry 2016 Volume 81(Issue 5) pp:1989-1997
Publication Date(Web):February 1, 2016
DOI:10.1021/acs.joc.5b02826
The mechanism and origin of selectivities in BF3·Et2O-catalyzed intermolecular [3 + 2] cycloadditions of propargylic alcohol and α-oxo ketene dithioacetals have been studied using density functional theory. Several possible reaction pathways were evaluated on the basis of two possible binding modes between the carbonyl or hydroxyl oxygen of substrates and catalyst. The preferred mechanism initiates dehydroxylation of propargylic alcohol by Lewis acid BF3 and generates active allenic carbocation species to provide the favorable electrophile. It then proceeds via four processes involving nucleophilic addition of Cα on α-oxo ketene dithioacetals to the C1 of active allenic carbocation intermediate, [1,4]-alkylthio shift, Hα-elimination, and intramolecular cyclization. This reaction sequence is in contrast to the mechanism by a previously published study, that is, [1,4]-alkylthio migration occurs prior to the cyclization. Our calculated results suggested that electrostatic attraction and hydrogen-bonding interactions between substrates and catalyst play a vital role in the [3 + 2] cycloaddition.
Co-reporter:Pin Xiao, Haiyan Yuan, Jianquan Liu, Yiying Zheng, Xihe Bi, and Jingping Zhang
ACS Catalysis 2015 Volume 5(Issue 10) pp:6177
Publication Date(Web):September 10, 2015
DOI:10.1021/acscatal.5b01703
A combined DFT and experimental study was performed to reveal the mechanism of isocyanide-alkyne cycloaddition. Our results indicate that the mechanism of this valuable reaction is an unexpected multicatalyzed radical process. Ag2CO3 is the pivotal catalyst, serving as base for the deprotonation of isocyanide and oxidant to initiate the initial isocyanide radical formation. After the cycloaddition between isocyanide radical and silver-acetylide, substrate (isocyanide) and solvent (dioxane) replace the role of Ag2CO3. They act as a radical shuttle to regenerate isocyanide radical for the next catalytic cycle, simultaneously completing the protonation. Furthermore, the bulk solvent effect significantly increases the reactivity by decreasing the activation barriers through the whole reaction, serving as solvent as well as catalyst.Keywords: Ag2CO3; DFT; multicatalysis; pyrrole; radical mechanism
Co-reporter:Chao-Ying Fan, Pin Xiao, Huan-Huan Li, Hai-Feng Wang, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie, and Jing-Ping Zhang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 50) pp:27959
Publication Date(Web):December 1, 2015
DOI:10.1021/acsami.5b10300
In this work, the chemical interaction of cathode and lithium polysulfides (LiPSs), which is a more targeted approach for completely preventing the shuttle of LiPSs in lithium–sulfur (Li–S) batteries, has been established on the electrode level. Through simply posttreating the ordinary sulfur cathode in atmospheric environment just for several minutes, the Au nanoparticles (Au NPs) were well-decorated on/in the surface and pores of the electrode composed of commercial acetylene black (CB) and sulfur powder. The Au NPs can covalently stabilize the sulfur/LiPSs, which is advantageous for restricting the shuttle effect. Moreover, the LiPSs reservoirs of Au NPs with high conductivity can significantly control the deposition of the trapped LiPSs, contributing to the uniform distribution of sulfur species upon charging/discharging. The slight modification of the cathode with <3 wt % Au NPs has favorably prospered the cycle capacity and stability of Li–S batteries. Moreover, this cathode exhibited an excellent anti-self-discharge ability. The slight decoration for the ordinary electrode, which can be easily accessed in the industrial process, provides a facile strategy for improving the performance of commercial carbon-based Li–S batteries toward practical application.Keywords: anti-self-discharge; Au nanoparticles; chemical Au−S interaction; Li−S batteries; postdecorated cathodes
Co-reporter:Shamsa Bibi and Jingping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 12) pp:7986-7999
Publication Date(Web):19 Feb 2015
DOI:10.1039/C4CP05814C
A series of conjugated donor molecules (DmAnSq where m = 1–4, n = 1–7 while D = benzodithiophene, A = benzooxadiazole and S denotes ethyne spacers between D and A or D and D fragments) with various ratios of D/A fragments and topologies have been designed and investigated for OPV applications. An increase in the ratio of the acceptor fragment with respect to the donor fragment decreases the LUMO energy level and narrows the Eg for the designed molecule. More vertically (C4 and C8 substituted phenyl ring positions) bonded acceptor fragments than linearly (C2 and C6 substituted thiophene ring positions) bonded fragments result in a significant red shift in the maximum absorption wavelength. While, linearly bonded fragments lead to stronger absorption bands. Molecules with D–A–D topology exhibit more significant optical and electronic characteristics than those with D–D topology. All donor molecules (m = 2–4) of the D–A–D type show lower λh values than those of 1 donor containing (DAn) molecules. D–D type molecules show only lower λe values than DAn molecules because of the presence of a second donor fragment. The charge transfer phenomenon is shape dependent. The branched or anisotropic X, H, π, n, and square shaped molecules display higher charge transfer rates than the corresponding linear isomers due to better dimensionality. On the basis of these results, we suggest that designed donor and corresponding matched acceptor molecules have potential to act as promising candidates in solar cell devices.
Co-reporter:Jing Lu, Yiying Zheng and Jingping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 30) pp:20014-20020
Publication Date(Web):03 Jul 2015
DOI:10.1039/C5CP02810H
A series of donor–acceptor compounds, including asymmetric D–B–Ai–B and symmetric D–B–Ai–B–D topologies, have been designed and investigated using density functional theory and time dependent density functional theory toward highly efficient thermally activated delayed fluorescent (TADF) materials. Phenoxazine (PXZ) is adopted as a donor (D) fragment, while 1,3,4-oxadiazole (A1), benzo[c][1,2,5]thiadiazole (A2), and quinoxaline (A3) are selected as acceptor fragments. A phenyl ring (B) is connected to Ai to extend the π-conjugation, leading to strong electron-withdrawing ability. Our results indicate that the singlet–triplet energy gaps (ΔEST) of symmetric D–B–Ai–B–D compounds are smaller than those of asymmetric D–B–Ai–B ones. For the same topologic series, the ΔEST values decrease with increasing electron-withdrawing strength of B–Ai–B. The lowest ΔEST value has been obtained for D–B–A2–B–D among all these investigated compounds, which displays the most efficient up-conversion from triplet to singlet excited states. Then, the potential energy surface and normal mode analyses were applied to discuss the charge injection and transport characteristics. The designed D–B–Ai–B–D compounds exhibited more effective charge injection with a lower ionization potential and a higher electron affinity than D–B–Ai–B ones. Meanwhile, the temperature dependent mobility was predicted by Marcus theory, both hole and electron mobilities of D–B–Ai–B–D increase with increasing temperature in the range of 5–200 K. However, hole mobility slightly decreases from 200 K to 300 K. The newly designed D–B–A2–B–D compounds demonstrate higher electron and hole mobilities than D–B–A1–B–D, implying that the chemical modification of acceptors effectively improves the carrier transport ability. Our theoretical investigation might provide more chances to challenge the rational design of novel and high-performance TADF-based organic light emitting diodes.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Kang Wang, Xing-Long Wu, Hai-Zhu Sun and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 35) pp:22893-22899
Publication Date(Web):31 Jul 2015
DOI:10.1039/C5CP03505H
A novel kind of plum-pudding like mesoporous SiO2 nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method. Transmission electron microscopy (TEM) analysis showed that most of the MSNs were well anchored on FG. This special architecture has multiple advantages, including FG that offers a conductive framework and hinders the volume expansion effect. Moreover, the porous structure of MSNs could provide more available lithium storage sites and extra free space to accommodate the mechanical strain caused by the volume change during the repeated reversible reaction between Li+ and active materials. Due to the synergetic effects of its unique plum-pudding structure, the obtained pp-MSNs/FG nanocomposite exhibited a decent reversible capacity of 702 mA h g−1 (based on the weight of MSNs in the electrode material) after 100 cycles with high Coulombic efficiency above 99% under 100 mA g−1 and a charge capacity of 239.6 mA h g−1 could be obtained even under 5000 mA g−1. Their high rate performance is among the best-reported performances of SiO2-based anode materials.
Co-reporter:Chao-Ying Fan, Huan-Huan Li, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 36) pp:23481-23488
Publication Date(Web):06 Aug 2015
DOI:10.1039/C5CP02531A
The effect of graphene lateral size on the electrochemical performance of lithium–sulfur (Li–S) batteries is often ignored. In this study, the thermally exfoliated large lateral-sized graphene (denoted LTG) was employed as the conductive matrix to support sulfur, and its performance was then compared with that of a smaller lateral-sized graphene (denoted STG) for Li–S batteries. The results showed that the LTG–S composite exhibited much higher capacity retention (53%) versus the STG–S (29%) and better rate capabilities. Because they were both identical in morphology, in terms of sulfur content and sulfur distribution, the improved properties probably resulted from the potential prevention of polysulfide diffusion upon cycling due to the larger graphene-based network and higher aspect ratio of the LTG matrix, referred as better polysulfide reservoirs. To further improve the cell performance, a reduced graphene oxide-coated carbon fiber paper (RCF) was inserted between the LTG–S cathode and the separator by a simple drop-coat method, which provided an increased conductive surface area for polysulfides to be oxidized/reduced and buffered volume expansion. As expected, the discharge capacities of 1143 and 622 mA h g−1 at first use and after 100th cycles were obtained with an average Coulombic efficiency of 99.7%, which were higher than 847 and 455 mA h g−1 for the cathode without the RCF, respectively. This study highlights the significance of large graphene sheets and interlayers on the inhibition of polysulfide diffusion and offers a new way to solve the problems of Li–S batteries.
Co-reporter:Jing Lu, Yiying Zheng and Jingping Zhang
RSC Advances 2015 vol. 5(Issue 24) pp:18588-18592
Publication Date(Web):02 Feb 2015
DOI:10.1039/C4RA15155K
A theoretical investigation on the relationship between the electronic structures and emission properties of thermally activated delayed fluorescent materials based on donor–acceptor type spiro-acridine derivatives has been performed. Efficient color tuning over the whole visible range has been achieved via structural modification of the acceptor fragment.
Co-reporter:Huan-Huan Li
The Journal of Physical Chemistry C 2015 Volume 119(Issue 7) pp:3495-3501
Publication Date(Web):January 23, 2015
DOI:10.1021/jp511435w
Mesoporous SiO2 nanospheres (MSNs) and carbon nanocomposite with dual-porosity structure (DMSNs/C) were synthesized via a straightforward approach. Both MSNs and DMSNs/C showed uniform pore size distribution, high specific surface area, and large pore volume. When evaluated as an anode material for lithium ion batteries (LIBs), the DMSNs/C nanocomposite not only delivered an impressive reversible capacity of 635.7 mAh g–1 (based on the weight of MSNs in the electrode material) over 200 cycles at 100 mA g–1 with Coulombic efficiency (CE) above 99% but also exhibited excellent rate capability. The significant improvement of the electrochemical performance was attributed to synergetic effects of the dual-mesoporous structure and carbon coating layer: (i) the dual-porosity structure could increase the contact area and facilitate Li+ diffusion at the interface between the electrolyte and active materials, as well as buffer the volume change of MSNs, and (ii) the homogeneous carbon coating represented an excellent conductive layer, thus significantly speeding the lithiation process of the MSNs significantly, while further restraining the volume expansion. Considering the facile preparation and good lithium storage abilities, the DMSNs/C nanocomposite holds promise in applications in practical LIBs.
Co-reporter:Fang Wan, Xing-Long Wu, Jin-Zhi Guo, Jin-Yue Li, Jing-Ping Zhang, Li Niu, Rong-Shun Wang
Nano Energy 2015 Volume 13() pp:450-457
Publication Date(Web):April 2015
DOI:10.1016/j.nanoen.2015.03.017
•One nanosheet organic anode material (Na2C8H4O4) for SIBs is successfully prepared.•The nanosheet Na2C8H4O4 exhibits much improved electrochemical properties in comparison to the bulk one.•The reasons of improvement are disclosed by ex-situ FTIR, SEM and EIS.•One new one-step desodiation mechanism is found in the Na2C8H4O4 nanosheet system.Recently, room temperature sodium ion batteries (SIBs) have been considered as one of the optimal alternatives for lithium ion batteries although there are still many challenges to be solved. At the present stage, the research priorities for SIBs still focus on the development of various electrode materials to meet the applicability. In this communication, we have controllably prepared a superior anode material (disodium terephthalate, Na2C8H4O4) with nanosheet-like morphology, which exhibits much improved electrochemical properties in terms of larger reversible capacity (248 mA h/g vs. 199 mA h/g), higher rate capabilities (for instance, 1.55 times the bulk material at 1250 mA/g) and better cycling performance (105 mA h/g vs. 60 mA h/g after 100 cycles at 250 mA/g) in comparison with the bulk one prepared at the similar system without the addition of polar solvent dimethylformamide. More importantly, it is further disclosed that, these enhanced performances could be mainly due to the new one-step desodiation mechanism and optimized ionic/electronic transfer pathways in the nanosheet system through the analyses of ex-situ infrared spectra, cyclic voltammogram, galvanostatic curves, scanning electron microscope images and electrochemical impedance spectroscopy.
Co-reporter:Haiyan Yuan, Yiying Zheng, Zhongxue Fang, Xihe Bi and Jingping Zhang
Green Chemistry 2014 vol. 16(Issue 5) pp:2653-2663
Publication Date(Web):10 Feb 2014
DOI:10.1039/C3GC42259C
DFT investigations are carried out to improve the domino cyclization between gem-dialkylthio vinylallenes and benzylamine. Economic reaction approaches were explored, namely, this reaction can occur under organic solvent-free conditions either catalyzed by trace water or self-catalyzed by BnNH2. Three types of reactions (DMSO-assisted, trace water-catalyzed, and self-catalyzed by BnNH2) shared the same reaction mechanism with the nucleophilic attack of BnNH2 on the allenic carbon of thioamide intermediate Re. For trace water-catalyzed reaction another mechanism was also found that is the BnNH2 attacks the carbonyl carbon of the conformational isomer of Re. Among the investigated mechanisms, the trace water-catalyzed one is suggested to be the most efficient and convenient synthetic method for pyrroles. Our calculated results were further confirmed by the experimental observation, which opens a new strategy for the synthesis of pyrroles.
Co-reporter:Bo Li, Ning Jiang, Jumei Tian, Tingting Li, Guixiang Hou and Jingping Zhang
Dalton Transactions 2014 vol. 43(Issue 24) pp:9267-9270
Publication Date(Web):27 Mar 2014
DOI:10.1039/C4DT00703D
Our endeavors are devoted to the explanation of the nature of the magnetic relaxation phenomena in the herein prepared [MnII5(HPO4)2(PO4)2(H2O)4]n (1). The behavior investigation indicates the prominence of the half-occupied magnetic centers and the competence of the antiferromagnetic interactions and non-zero magnetic moments. The investigation suggests that the design and synthesis of unusual magnetic center materials with innate unquenched magnetic moments could provide a new route for the production of molecular magnets with magnetic relaxation.
Co-reporter:Jumei Tian, Bo Li, Xiaoying Zhang and Jingping Zhang
CrystEngComm 2014 vol. 16(Issue 6) pp:1071-1078
Publication Date(Web):08 Nov 2013
DOI:10.1039/C3CE41741G
Four new compounds, [Ni(HPO3)(4,4′-bpy)(H2O)3]·4H2O (1), [Co2(HPO3)2(4,4′-bpy)2(H2O)6]·9H2O (2), [Zn(HPO3)(4,4′-bpy)0.5]·H2O (3), and [Co3(PO3)2(4,4′-bpy)3(H2O)6]·3H2O (4), have been synthesized. Compounds 1 and 2 are linear chains and isostructural except for the distinction of the metal ion and the number of lattice water molecules. Compound 3 consists of a 2D sheet structure. Compound 4 is a 3D magnetic porous material with 1D channels along the c axis. Magnetic measurements indicate that compound 1 shows paramagnetic behavior, while compound 2 displays antiferromagnetic behavior. Compound 4 exhibits antiferromagnetism with a pronounced field-induced spin–flop transition. A critical field of 3 T at 2.0 K is determined from the derivative dM/dH curve. Meanwhile, compound 4 shows a strong spin frustration arising from the geometric frustration in the kagomé lattice. The dehydrated phase 4a displays a characteristic of N2 adsorption with type II isotherm. We performed detailed magnetic measurements for 4a, which exhibits quite different magnetic properties from 4. Compound 4a displays a ferrimagnetic behavior with a lower transition field of 0.2 T, and a weaker spin frustration.
Co-reporter:Fengmei Yang, Weiwei Sun, Yuhan Li, Haiyan Yuan, Zhiyong Dong, Huanhuan Li, Jumei Tian, Yiying Zheng and Jingping Zhang
RSC Advances 2014 vol. 4(Issue 91) pp:50195-50201
Publication Date(Web):02 Oct 2014
DOI:10.1039/C4RA06170E
The electrochemical properties of three isotopic Li2FePO4F compounds, as cathode materials under different space groups Pbcn, P and Pnma were investigated using first principle calculations. Their structures and average open circuit voltages for step delithiation reactions were explored, and the results are in good agreement with the reported experimental data. We estimate the substitution effect of Fe by Co in Pnma-Li2FePO4F. The substitution of Fe by Co in Li2Fe1−xCoxPO4F may enhance the discharge potential of the materials, and the rate of its volume change during the redox process is between 0.6% and 2.1%. Furthermore, from the projected density of states for Li2Fe0.5Co0.5PO4F, we found strong hybridization for Fe-3d and Co-3d bands near the Fermi level, which implies that the Co-doped Li2Fe1−xCoxPO4F may possess better electronic conductivity than the pure phase.
Co-reporter:Peng Mei, Xing-Long Wu, Haiming Xie, Liqun Sun, Yanping Zeng, Jingping Zhang, Linghua Tai, Xin Guo, Lina Cong, Shunchao Ma, Cen Yao and Rongshun Wang
RSC Advances 2014 vol. 4(Issue 49) pp:25494-25501
Publication Date(Web):15 May 2014
DOI:10.1039/C4RA02269F
Nowadays one of the principal challenges for the development of lithium-ion batteries (LIBs) is fulfilling the burgeoning demands for high energy and power density with long cycle life. Herein, we demonstrate a two-step route for synthesizing LiV3O8 nanorods with a confined preferential orientation by using VO2(B) nanosheets made in the laboratory as the precursor. The special structures of nanorods endow the LiV3O8 materials with markedly enhanced reversible capacities, high-rate capability and long-term cycling stability as cathodes for lithium storage. The results show that very desirable initial capacities of 161 and 158 mA h g−1 can be achieved for the LiV3O8 nanorods at extremely high rates of 2000 and 3000 mA g−1, with minimal capacity loss of 0.037% and 0.031% per cycle throughout 300 and 500 cycles, respectively. The energetically optimized electron conduction and lithium diffusion kinetics in the electrode process may shed light on the superior electrochemical properties of the LiV3O8 nanorods, primarily benefitting from the small particle size, large surface area and restricted preferential ordering along the (100) plane.
Co-reporter:Huan-Huan Li, Jia-Wei Wang, Xing-Long Wu, Hai-Zhu Sun, Feng-Mei Yang, Kang Wang, Lin-Lin Zhang, Chao-Ying Fan and Jing-Ping Zhang
RSC Advances 2014 vol. 4(Issue 68) pp:36218-36225
Publication Date(Web):06 Aug 2014
DOI:10.1039/C4RA07043G
A novel method was developed to successfully prepare mesoporous Si/C nanocomposites with yolk–shell structures (MSi@C). Different from the reported methods, this approach was unique, straightforward and easily scaled up. A plausible mechanism for the formation of MSi@C nanocomposites was proposed, which was in accordance with the results of transmission electron microscopy (TEM). When the mixture of mesoporous Si (M-Si) and citric acid was heated up, the volume of air adsorbed by the M-Si expanded, and the viscoelastic citric acid layers inflated just like balloons, directly leading to the formation of the yolk–shell structured MSi@C nanocomposites during the carbonization. The MSi@C nanocomposites possessed an M-Si core with diameter ∼150 nm and a carbon shell with diameter ∼230 nm. Such nano and mesoporous structure combined with voids between the M-Si core and carbon shell not only provides enough space for the volume expansion of M-Si during lithiation, but also accommodates the mechanical stresses/strains caused by the volume inflation and contraction. Moreover, partial graphitization of the carbon contributed to the improved electrical conductivity and rate performance of MSi@C. As a result, the prepared MSi@C exhibited an initial reversible capacity of 2599.1 mA h g−1 and maintained 1264.7 mA h g−1 even after 150 cycles at 100 mA g−1, with high coulombic efficiency (CE) above 99% (based on the weight of M-Si in the electrode). Therefore, this work provided an alternative method to fabricate yolk–shell nanostructured materials with great potential as anode materials for lithium ion batteries.
Co-reporter:Dr. Wenliang Li;Haijie Shi; Jingping Zhang
ChemPhysChem 2014 Volume 15( Issue 9) pp:1772-1778
Publication Date(Web):
DOI:10.1002/cphc.201400064
Abstract
Porous aromatic frameworks (PAFs) are novel materials with diamond topology. With the aim of enhancing their CO2 capture and storage capacity and investigating the effect of nitrogen and/or -COOH decorations on CO2 adsorption in PAFs, a series of N-containing PAFs were designed based on ab initio results. The interaction energies (Eint) between CO2 and each six-membered ring were calculated at the B2PLYP-D2/def2-TZVPP level, then the six-membered rings with high CO2-binding affinity were selected and used in the PAFs. To explore the performance of the designed PAFs, the CO2 uptake, selectivity of CO2 over CH4, H2, and N2, and the Eint value of CO2 in PAFs were investigated by using grand canonical Monte Carlo (GCMC) simulations and ab initio calculations. This work shows that pyridine with one nitrogen atom can provide a strong physisorption site for CO2, whereas more nitrogen atoms in heterocycles will reduce the interaction, especially at relatively low pressure. PAFs with COOH groups show high CO2 capacity. Our work provides an efficient way to understand the adsorption mechanism and a supplemental approach to experimental work.
Co-reporter:Shamsa Bibi, Ping Li and Jingping Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 44) pp:13828-13841
Publication Date(Web):10 Sep 2013
DOI:10.1039/C3TA12421E
Employing a double overlapping wave band strategy based on DFT, five X-shaped anisotropic low energy gap donor compounds (D1–D5) have been designed for solar cell applications. A series of new PDI acceptor molecules are built to match each designed donor in terms of frontier molecular orbital energy levels by tuning substituents at P1 and P2 positions of PDI1. The designed donors consist of a central electron donor fragment benzodithiophene (DF), electron accepting fragments (A1 to A5) and terfuran and ethynyl-terfuran bridges (B1 and B2 respectively). The absorption bands of the designed donors based on TD-DFT not only cover the visible region but also extend to the infrared region of the spectrum. The donor fragment DF and multibranched spacers B1 and B2 are responsible for absorption in short and middle wavelength regions while the acceptor fragments contribute to the middle and long wavelength regions of the spectrum. In addition, PDIs also exhibit complementary absorptions in the visible range of the solar spectrum. Among designed donors, D1 exhibits ideal lowest band gap, FMO energy levels and exclusive broadest absorption because of the strongest electron withdrawing fragment. The lower λe values as compared to λh illustrate that these five donors would be favorable for electron transfer. The carrier mobility of D1 in the crystalline state has been predicted using the P21/c space group. D1 displays higher carrier mobility for μe = 2.00 cm2 V−1 s−1 and μh = 1.7 × 10−2 cm2 V−1 s−1. The calculated Voc of D1 is 1.02 V. The designed donors and PDI acceptors are suitable and recommended for high performance solar cell devices.
Co-reporter:Yiying Zheng, Tao Xiong, Yunhe Lv, Jingping Zhang and Qian Zhang
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 45) pp:7923-7930
Publication Date(Web):19 Sep 2013
DOI:10.1039/C3OB41299G
A combination of computational and experimental methods was carried out to elucidate the mechanism of palladium-catalyzed water-assisted benzylic C–H amination with N-fluorobenzenesulfonimide (NFSI), which involved the oxidative addition of PdII to PdIV-species as a rate-limiting step, followed by water-assisted concerted metalation–deprotonation (CMD) of the PdIV complex and water-assisted reductive elimination (RE) processes, and then a nucleophilic addition process to generate the final product and complete the catalytic cycle. The stability of the PdIV complex could be ascribed to the suitable ligands with strong σ-donors and resistance to decomposition, as well as being sufficiently bulky because the water-clusters assembled the ligands through hydrogen bonds to act as one multidentate ligand. Calculation results suggested that water also plays a crucial role as a proton transferring bridge in water-assisted CMD and RE processes. The corresponding experimental findings substantiate the expectation. Additionally, NFSI was found to act as both the oxidant and the nitrogen source to facilitate the reaction, while the steric effect of the bulky –N(SO2Ph)2 group contributed to circumventing the o-C–H amination. In this reaction, we investigated a novel spiro-cyclopalladation intermediate, formed by the reaction of the PdIV centre with pristine-carbon instead of ortho-carbon, which might be valuable for our understanding and further development of transition metal catalyzed C–H functionalization.
Co-reporter:Fang Wan, Hong-Yan Lü, Xing-Long Wu, Xin Yan, Jin-Zhi Guo, Jing-Ping Zhang, Guang Wang, Dong-Xue Han, Li Niu
Energy Storage Materials (October 2016) Volume 5() pp:214-222
Publication Date(Web):1 October 2016
DOI:10.1016/j.ensm.2016.06.003
To make alloying anodes be practicability for lithium-ion batteries, graphene-incorporation has been demonstrated as one of the most effective strategies. However, successive lithiation/delithiation would usually lead to the detachment and self-aggregation of active alloying nanoparticles and graphene. Herein, an oxygen-bonds-bridging (Sn–O–C) Sn/graphene (Sn–O–G) micro/nanocomposite, in which Sn particles are in the ultrasmall scale of <3 nm and embedded in graphene-based microspheres, was prepared via an in-situ co-reduction procedure. Electrochemical tests demonstrated that the Sn–O–G exhibited much improved Li-storage properties in terms of high reversible capacity (1246 mA h/g at 50 mA/g), superior high-rate capabilities (220 mA h/g at 16 A/g) and long-term cycle life (410 mA h/g after 2000 cycles at 4 A/g) in comparison to the Sn/graphene (Sn/G) prepared from the similar procedures just without the presence of Sn–O–C bonds. Because of the same morphology, size and microstructures of both Sn-based anodes, it is speculated that such enhanced properties of Sn–O–G should be benefited from the Sn–O–C bonds. In order to answer “Do the bridging oxygen bonds between active Sn nanodots and graphene improve the Li-storage properties?”, several ex-situ technologies were employed to track the physicochemical and electrochemical variation of Sn–O–G electrodes, revealing the reversibility of breaking/re-formation and durability of Sn–O–C bonds during the successive Li-insertion/extraction. Therefore, the answer is “YES”.Download full-size image
Co-reporter:Lin Zhang, Pin Xiao, Xiaoxue Guan, Zhouliang Huang, Jingping Zhang and Xihe Bi
Organic & Biomolecular Chemistry 2017 - vol. 15(Issue 7) pp:NaN1583-1583
Publication Date(Web):2017/01/17
DOI:10.1039/C7OB00019G
The radical coupling of isocyanides and alcohols/phenols promoted by silver in the presence of water is reported for the first time, which led to the formation of diverse carbamates. In contrast to the well-known 1,1-addition to form imidoyl radicals, a novel reaction mechanism, involving sequential hydration of isocyanides and coupling with alkoxyl/phenoxyl radicals, is disclosed by combining experimental and theoretical studies.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Xing-Long Wu, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 6) pp:NaN2059-2059
Publication Date(Web):2016/01/07
DOI:10.1039/C5TA08779A
A dissolution–recrystallization method was developed to prepare flexible paper electrodes constructed of Zn2GeO4 nanofibers anchored with amorphous carbon (ZGO/C-P) for high energy and power Li-ion batteries. The ZGO/C-P exhibits superior long-term cycle stability (up to 2000 cycles at 1 A g−1) and excellent rate capability.
Co-reporter:Chao-Ying Fan, Si-Yu Liu, Huan-Huan Li, Yan-Hong Shi, Han-Chi Wang, Hai-Feng Wang, Hai-Zhu Sun, Xing-Long Wu and Jing-Ping Zhang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 22) pp:NaN11262-11262
Publication Date(Web):2017/05/08
DOI:10.1039/C7TA02231J
Although the composite of metal oxide and porous carbon has been confirmed as an effective material to chemically adsorb polysulfides, the low conductivity of the metal oxide results in the need for extra pathways for the diffusion of polysulfides from adsorption sites to redox-active sites. This process results in sluggish reaction kinetics and escaped polysulfides. In this work, a Gerber tree-like interlayer with multiple components was designed to fully mediate the electrochemical conversion of Li–S batteries and shorten the diffusion distance of polysulfides in the composite. The branches of the interlayer contained TiO2 and Co3O4 nanocrystals embedded into N-doped porous carbon, while the fruit was catalytic metal cobalt. The two co-existing chemical adsorbents ensure the restriction of polysulfides through S–Ti–O bonding and Lewis acid–base interaction. Moreover, the metal Co catalyzes the transformation of adsorbed polysulfides into low-order ones, which largely shortens the diffusion pathway, improving the reaction kinetics and preventing the migration of polysulfides. The cell with the interlayer exhibited outstanding electrochemical performance. After 100 cycles, a reversible capacity of 968 mA h g−1 was maintained at 0.1C with a stable capacity retention of 85%. Even at the current rate of 1C, the cell delivered a capacity of 684.5 mA h g−1 after 300 cycles.
Co-reporter:Yiying Zheng, Tao Xiong, Yunhe Lv, Jingping Zhang and Qian Zhang
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 45) pp:NaN7930-7930
Publication Date(Web):2013/09/19
DOI:10.1039/C3OB41299G
A combination of computational and experimental methods was carried out to elucidate the mechanism of palladium-catalyzed water-assisted benzylic C–H amination with N-fluorobenzenesulfonimide (NFSI), which involved the oxidative addition of PdII to PdIV-species as a rate-limiting step, followed by water-assisted concerted metalation–deprotonation (CMD) of the PdIV complex and water-assisted reductive elimination (RE) processes, and then a nucleophilic addition process to generate the final product and complete the catalytic cycle. The stability of the PdIV complex could be ascribed to the suitable ligands with strong σ-donors and resistance to decomposition, as well as being sufficiently bulky because the water-clusters assembled the ligands through hydrogen bonds to act as one multidentate ligand. Calculation results suggested that water also plays a crucial role as a proton transferring bridge in water-assisted CMD and RE processes. The corresponding experimental findings substantiate the expectation. Additionally, NFSI was found to act as both the oxidant and the nitrogen source to facilitate the reaction, while the steric effect of the bulky –N(SO2Ph)2 group contributed to circumventing the o-C–H amination. In this reaction, we investigated a novel spiro-cyclopalladation intermediate, formed by the reaction of the PdIV centre with pristine-carbon instead of ortho-carbon, which might be valuable for our understanding and further development of transition metal catalyzed C–H functionalization.
Co-reporter:Shamsa Bibi and Jingping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 12) pp:NaN7999-7999
Publication Date(Web):2015/02/19
DOI:10.1039/C4CP05814C
A series of conjugated donor molecules (DmAnSq where m = 1–4, n = 1–7 while D = benzodithiophene, A = benzooxadiazole and S denotes ethyne spacers between D and A or D and D fragments) with various ratios of D/A fragments and topologies have been designed and investigated for OPV applications. An increase in the ratio of the acceptor fragment with respect to the donor fragment decreases the LUMO energy level and narrows the Eg for the designed molecule. More vertically (C4 and C8 substituted phenyl ring positions) bonded acceptor fragments than linearly (C2 and C6 substituted thiophene ring positions) bonded fragments result in a significant red shift in the maximum absorption wavelength. While, linearly bonded fragments lead to stronger absorption bands. Molecules with D–A–D topology exhibit more significant optical and electronic characteristics than those with D–D topology. All donor molecules (m = 2–4) of the D–A–D type show lower λh values than those of 1 donor containing (DAn) molecules. D–D type molecules show only lower λe values than DAn molecules because of the presence of a second donor fragment. The charge transfer phenomenon is shape dependent. The branched or anisotropic X, H, π, n, and square shaped molecules display higher charge transfer rates than the corresponding linear isomers due to better dimensionality. On the basis of these results, we suggest that designed donor and corresponding matched acceptor molecules have potential to act as promising candidates in solar cell devices.
Co-reporter:Shamsa Bibi, Ping Li and Jingping Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 44) pp:NaN13841-13841
Publication Date(Web):2013/09/10
DOI:10.1039/C3TA12421E
Employing a double overlapping wave band strategy based on DFT, five X-shaped anisotropic low energy gap donor compounds (D1–D5) have been designed for solar cell applications. A series of new PDI acceptor molecules are built to match each designed donor in terms of frontier molecular orbital energy levels by tuning substituents at P1 and P2 positions of PDI1. The designed donors consist of a central electron donor fragment benzodithiophene (DF), electron accepting fragments (A1 to A5) and terfuran and ethynyl-terfuran bridges (B1 and B2 respectively). The absorption bands of the designed donors based on TD-DFT not only cover the visible region but also extend to the infrared region of the spectrum. The donor fragment DF and multibranched spacers B1 and B2 are responsible for absorption in short and middle wavelength regions while the acceptor fragments contribute to the middle and long wavelength regions of the spectrum. In addition, PDIs also exhibit complementary absorptions in the visible range of the solar spectrum. Among designed donors, D1 exhibits ideal lowest band gap, FMO energy levels and exclusive broadest absorption because of the strongest electron withdrawing fragment. The lower λe values as compared to λh illustrate that these five donors would be favorable for electron transfer. The carrier mobility of D1 in the crystalline state has been predicted using the P21/c space group. D1 displays higher carrier mobility for μe = 2.00 cm2 V−1 s−1 and μh = 1.7 × 10−2 cm2 V−1 s−1. The calculated Voc of D1 is 1.02 V. The designed donors and PDI acceptors are suitable and recommended for high performance solar cell devices.
Co-reporter:Huan-Huan Li, Zi-Yao Li, Xing-Long Wu, Lin-Lin Zhang, Chao-Ying Fan, Hai-Feng Wang, Xiao-Ying Li, Kang Wang, Hai-Zhu Sun and Jing-Ping Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 21) pp:NaN8248-8248
Publication Date(Web):2016/04/18
DOI:10.1039/C6TA02417C
In recent years, metal-organic compounds have been considered as ideal sacrificial templates to obtain transition metal oxides for electrochemical applications due to their diverse structures and tunable properties. In this work, a new kind of cobalt-based metal organic compound with a layered structure was designed and prepared, which was then transformed into ultrafine cobalt oxide (Co3O4) nanocrystallites via a facile annealing treatment. The obtained Co3O4 nanocrystallites further assembled into a hierarchical shale-like structure, donating extremely short ion diffusion pathway and rich porosity to the materials. The special structure largely alleviated the problems of Co3O4 such as inferior intrinsic electrical conductivity, poor ion transport kinetics and large volume changes during the redox reactions. When evaluated as anode materials for lithium-ion batteries, the shale-like Co3O4 (S-Co3O4) exhibited superior lithium storage properties with a high capacity of 1045.3 mA h g−1 after 100 cycles at 200 mA g−1 and good rate capabilities up to 10 A g−1. Moreover, the S-Co3O4 showed decent electrochemical performance in sodium-ion batteries due to the above-mentioned comprehensive merits (380 and 153.8 mA h g−1 at 50 and 5000 mA g−1, respectively).
Co-reporter:Bo Li, Ning Jiang, Jumei Tian, Tingting Li, Guixiang Hou and Jingping Zhang
Dalton Transactions 2014 - vol. 43(Issue 24) pp:NaN9270-9270
Publication Date(Web):2014/03/27
DOI:10.1039/C4DT00703D
Our endeavors are devoted to the explanation of the nature of the magnetic relaxation phenomena in the herein prepared [MnII5(HPO4)2(PO4)2(H2O)4]n (1). The behavior investigation indicates the prominence of the half-occupied magnetic centers and the competence of the antiferromagnetic interactions and non-zero magnetic moments. The investigation suggests that the design and synthesis of unusual magnetic center materials with innate unquenched magnetic moments could provide a new route for the production of molecular magnets with magnetic relaxation.
Co-reporter:Chao-Ying Fan, Huan-Huan Li, Lin-Lin Zhang, Hai-Zhu Sun, Xing-Long Wu, Hai-Ming Xie and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 36) pp:NaN23488-23488
Publication Date(Web):2015/08/06
DOI:10.1039/C5CP02531A
The effect of graphene lateral size on the electrochemical performance of lithium–sulfur (Li–S) batteries is often ignored. In this study, the thermally exfoliated large lateral-sized graphene (denoted LTG) was employed as the conductive matrix to support sulfur, and its performance was then compared with that of a smaller lateral-sized graphene (denoted STG) for Li–S batteries. The results showed that the LTG–S composite exhibited much higher capacity retention (53%) versus the STG–S (29%) and better rate capabilities. Because they were both identical in morphology, in terms of sulfur content and sulfur distribution, the improved properties probably resulted from the potential prevention of polysulfide diffusion upon cycling due to the larger graphene-based network and higher aspect ratio of the LTG matrix, referred as better polysulfide reservoirs. To further improve the cell performance, a reduced graphene oxide-coated carbon fiber paper (RCF) was inserted between the LTG–S cathode and the separator by a simple drop-coat method, which provided an increased conductive surface area for polysulfides to be oxidized/reduced and buffered volume expansion. As expected, the discharge capacities of 1143 and 622 mA h g−1 at first use and after 100th cycles were obtained with an average Coulombic efficiency of 99.7%, which were higher than 847 and 455 mA h g−1 for the cathode without the RCF, respectively. This study highlights the significance of large graphene sheets and interlayers on the inhibition of polysulfide diffusion and offers a new way to solve the problems of Li–S batteries.
Co-reporter:Huan-Huan Li, Lin-Lin Zhang, Chao-Ying Fan, Kang Wang, Xing-Long Wu, Hai-Zhu Sun and Jing-Ping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 35) pp:NaN22899-22899
Publication Date(Web):2015/07/31
DOI:10.1039/C5CP03505H
A novel kind of plum-pudding like mesoporous SiO2 nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method. Transmission electron microscopy (TEM) analysis showed that most of the MSNs were well anchored on FG. This special architecture has multiple advantages, including FG that offers a conductive framework and hinders the volume expansion effect. Moreover, the porous structure of MSNs could provide more available lithium storage sites and extra free space to accommodate the mechanical strain caused by the volume change during the repeated reversible reaction between Li+ and active materials. Due to the synergetic effects of its unique plum-pudding structure, the obtained pp-MSNs/FG nanocomposite exhibited a decent reversible capacity of 702 mA h g−1 (based on the weight of MSNs in the electrode material) after 100 cycles with high Coulombic efficiency above 99% under 100 mA g−1 and a charge capacity of 239.6 mA h g−1 could be obtained even under 5000 mA g−1. Their high rate performance is among the best-reported performances of SiO2-based anode materials.
Co-reporter:Jing Lu, Yiying Zheng and Jingping Zhang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 30) pp:NaN20020-20020
Publication Date(Web):2015/07/03
DOI:10.1039/C5CP02810H
A series of donor–acceptor compounds, including asymmetric D–B–Ai–B and symmetric D–B–Ai–B–D topologies, have been designed and investigated using density functional theory and time dependent density functional theory toward highly efficient thermally activated delayed fluorescent (TADF) materials. Phenoxazine (PXZ) is adopted as a donor (D) fragment, while 1,3,4-oxadiazole (A1), benzo[c][1,2,5]thiadiazole (A2), and quinoxaline (A3) are selected as acceptor fragments. A phenyl ring (B) is connected to Ai to extend the π-conjugation, leading to strong electron-withdrawing ability. Our results indicate that the singlet–triplet energy gaps (ΔEST) of symmetric D–B–Ai–B–D compounds are smaller than those of asymmetric D–B–Ai–B ones. For the same topologic series, the ΔEST values decrease with increasing electron-withdrawing strength of B–Ai–B. The lowest ΔEST value has been obtained for D–B–A2–B–D among all these investigated compounds, which displays the most efficient up-conversion from triplet to singlet excited states. Then, the potential energy surface and normal mode analyses were applied to discuss the charge injection and transport characteristics. The designed D–B–Ai–B–D compounds exhibited more effective charge injection with a lower ionization potential and a higher electron affinity than D–B–Ai–B ones. Meanwhile, the temperature dependent mobility was predicted by Marcus theory, both hole and electron mobilities of D–B–Ai–B–D increase with increasing temperature in the range of 5–200 K. However, hole mobility slightly decreases from 200 K to 300 K. The newly designed D–B–A2–B–D compounds demonstrate higher electron and hole mobilities than D–B–A1–B–D, implying that the chemical modification of acceptors effectively improves the carrier transport ability. Our theoretical investigation might provide more chances to challenge the rational design of novel and high-performance TADF-based organic light emitting diodes.
