Ln3+-doped fluoride is a far efficient material for realizing multicolor emission, which plays an important part in full-color displays, biolabeling, and MRI. However, studies on the multicolor tuning properties of Ln3+-doped fluoride are mainly concentrated on a complicated process using three or more dopants, and the principle of energy transfer mechanism is still unclear. Herein, multicolor tunable emission is successfully obtained only by codoping with Tb3+ and Eu3+ ions in β-NaGdF4 submicrocrystals via a facile hydrothermal route. Our work reveals that various emission colors can be obtained and tuned from red, orange-red, pink, and blue-green to green under single excitation energy via codoping Tb3+ and Eu3+ with rationally changed Eu3+/Tb3+ molar ratio due to the energy transfer between Tb3+ and Eu3+ ions in the β-NaGdF4 host matrix. Meanwhile, the energy transfer mechanism in β-NaGdF4: x Eu3+/y Tb3+ (x + y = 5 mol %) submicrocrystals is investigated. Our results evidence the potential of the dopants’ distribution density as an effective way for analyzing energy transfer and multicolor-controlled mechanism in other rare earth fluoride luminescence materials. Discussions on the multicolor luminescence under a certain dopant concentration based on single host and wavelength excitation are essential toward the goal of the practical applications in the field of light display systems and optoelectronic devices.Keywords: codoped; energy transfer; multicolor emission; tunable; β-NaGdF4 submicrocrystals;

Cu2SnS3 is considered as an emerging potential candidate for electrode materials due to considerable interlayer spaces and tunnels in its crystal structures and excellent conducting ability. Ternary Cu2SnS3 as anode in lithium ion batteries has already been reported, but it is rarely mentioned to be applied in supercapacitors which is considered to be a complementary energy storage device for lithium ion batteries. It is an effective method to improve the electrochemical performance of materials by adjusting the morphology and microstructure of materials. In present study, ternary nanosheet-assembled Cu2SnS3 microspheres (M-CTS) and nanoparticles-like Cu2SnS3 (N-CTS) are synthesized via a facile solvothermal route. The results suggest that Cu2SnS3 microspheres (M-CTS) exhibit better capacitive performance compared with Cu2SnS3 (N-CTS) nanoparticles, which means that morphology does have a significant effect on the electrochemical reaction. M-CTS presents excellent supercapacitor performances with the high specific capacity of about 406 C g–1 at a current density of 1 A g–1 and achieves a high energy density of 85.6 W h kg–1 and power density of 720 W kg–1. The remarkable electrochemical performance of Cu2SnS3 can be attributed to the large specific surface area, smaller average pore size, and improved electrical conductivity. Our research indicates that it is very suitable for large-scale production and has enormous potential in the practical application of high-performance supercapacitors.Keywords: Cu2SnS3; high performance; microspheres; morphology; supercapacitor;

Monoclinic LiFe(WO4)2 microcrystals have been fabricated by solid-state ceramic method. Microstructures, luminescent and magnetic properties of the as- fabricated microcrystals were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy and Vibrating Sample Magnetometer. Influence of sintering temperature and sintering time on the microstructures, luminescent and magnetic properties of LiFe(WO4)2 microcrystals were studied. Below the sintering temperature 800 °C, the prepared samples exhibited spherical-like morphology. The crystallinity and purity of the microcrystals increased with increasing the sintering temperature. At higher 800 °C, the observed morphology of the obtained microcrystalline turned to be rods-like. All the LiFe(WO4)2 microcrystals exhibit the alike broad emission peak centered at 390 nm under excitation of 242 nm ultraviolet light except for difference in emission intensity. Due to the good crystallinity and microstructures, LiFe(WO4)2 microcrystals fabricated at 800 °C possess the maximum emission intensity. On the premise of the optimal sintering temperature (800 °C) and the predetermined range of sintering time (1–9 h), the sintering time has little influence on the microstructures and luminescent properties of the LiFe(WO4)2 microcrystals. In addition, all the well crystallized LiFe(WO4)2 microcrystals exhibit paramagnetism at room temperature.

Sulfur compounds have been considered as potential thermoelectric materials due to recently reported high ZT values. However, the synthetic methods for these compounds are too expensive or complicated to be applied to large-scale production. Among these compounds, tin sulfide (SnS) has attracted increasing attention not only because of its extremely low thermal conductivity (below 1.0 W (m K)−1) but also its earth-abundant resources. Mechanical alloying and solvothermal method have been adopted to synthesize SnS as thermoelectric materials, but these preparation processes are either expensive or complicated. Here, a simple chemical precipitation method was developed to synthesize high-performance SnS by using analytically pure compounds as raw materials. The highest ZT value of 0.41 with a very low thermal conductivity of 0.29 W (m K)−1 and a large Seebeck coefficient of 403 μV K−1 is obtained at 848 K. The ZT value is two times higher than that of SnS samples synthesized by mechanical alloying, and our work provides a simple new method to obtain SnS with high ZT value, which will help its mass production in the future.

Sulfur compounds have been considered as potential thermoelectric materials due to recently reported high ZT values. However, the synthetic methods for these compounds are too expensive or complicated to be applied to large-scale production. Among these compounds, tin sulfide (SnS) has attracted increasing attention not only because of its extremely low thermal conductivity (below 1.0 W (m K)−1) but also its earth-abundant resources. Mechanical alloying and solvothermal method have been adopted to synthesize SnS as thermoelectric materials, but these preparation processes are either expensive or complicated. Here, a simple chemical precipitation method was developed to synthesize high-performance SnS by using analytically pure compounds as raw materials. The highest ZT value of 0.41 with a very low thermal conductivity of 0.29 W (m K)−1 and a large Seebeck coefficient of 403 μV K−1 is obtained at 848 K. The ZT value is two times higher than that of SnS samples synthesized by mechanical alloying, and our work provides a simple new method to obtain SnS with high ZT value, which will help its mass production in the future.

Herein, Sn was successfully doped into the Sb site of n-type NbCoSb half-Heusler compounds to tune the carrier concentration, and a maximum ZT value of ∼0.56 was obtained at 973 K for NbCoSb1−xSnx with x = 0.2, an increase of ∼40% as compared to that of NbCoSb. This enhancement is mainly attributed to the reduced carrier concentration by Sn doping, leading to a doubled Seebeck coefficient at 300 K. More importantly, the total thermal conductivity was reduced with Sn doping, and the reduction was mainly due to the lowered electron thermal conductivity. The decreased electron thermal conductivity resulted from the reduced carrier concentration and the consequent enhanced carrier degeneracy, contributing to a reduced Lorenz constant. A quantitative description of the electron transport characteristics was performed under a single parabolic band model supposing that the acoustic phonon scattering was dominant in the carrier transport. A high density of the state effective mass, m* ≈ 10 me, and relatively high deformation potential Edef = 21 eV were found for the solid solutions.

The exploration of localized surface plasmon resonance (LSPR) beyond the usual visible waveband, for example within the ultraviolet (UV) or deep-ultraviolet (D-UV) regions, is of great significance due to its unique applications in secret communications and optics. However, it is still challenging to universally synthesize the corresponding metal nanostructures due to their high activity. Herein, we report a universal, eco-friendly, facile and rapid synthesis of various nano-metals encapsulated by ultrathin carbon shells, significantly with a remarkable deep-UV LSPR characteristic, via a liquid-phase laser fabrication method. Firstly, a new generation of the laser ablation in liquid (LAL) method has been developed with an emphasis on the elaborate selection of solvents to generate ultrathin carbon shells, and hence to stabilize the formed metal nanocrystals. As a result, a series of metal@carbon nanoparticles (NPs), including Cr@C, Ti@C, Fe@C, V@C, Al@C, Sn@C, Mn@C and Pd@C, can be fabricated by this modified LAL method. Interestingly, these NPs exhibit LSPR peaks in the range of 200–330 nm, which are very rare for localized surface plasmon resonance. Consequently, the UV plasmonic effects of these metal@carbon NPs were demonstrated both by the observed enhancement in UV photoluminescence (PL) from the carbon nanoshells and by the improvement of the photo-responsivity of UV GaN photodetectors. This work could provide a universal method for carbon shelled metal NPs and expand plasmonics into the D-UV waveband.

The facile preparation of catalysts for high-purity helical carbon nanotubes (HCNTs) remains an open research problem. A novel catalyst precursor ferrous tartrate (C4H4O6Fe) obtained by one-step chemical synthesis is investigated in this study. The influence of reaction temperature on the morphology of the precursor's decomposition products under H2 is analyzed while Fe particles with a macroporous structure are obtained. HCNTs with a coil diameter and coil pitch of about 0.26 μm and 0.28 μm are achieved using C4H4O6Fe as catalyst precursor at 550 °C. Interestingly, Fe particles with different crystal faces were observed. In addition, electrochemical double-layer capacitors (EDLCs) utilizing HCNTs obtained at 550 °C as electrode materials are assembled exhibiting an enhanced specific capacitance of 95 F g−1 after acid treatment at 0.1 A g−1 in Na2SO4.

Well-defined 3D nitrogen-doped porous carbon materials (NPCMs) have been obtained from CQDs and melamine by the self-assembly process, presenting a distinct textural structure with uniform N-doping distribution. The as-prepared NPCMs, as the anode materials for SIBs, display high specify capacity, long-term cyclability and good rate capacity. At 100 mA g−1, the NPCM electrode can reach the first capacity of 225 mA h g−1 (204.7 mA h cm−2) and maintain 241.2 mA h g−1 (219.3 mA h cm−2) after 100 cycles. Even at the current density of 1000 mA g−1, a reversible capacity of 130.2 mA h g−1 (118.9 mA h cm−2) can be retained, which can be attributed to the improved extrinsic defects and electrical conductivity resulting from N-doping.

Earth-abundant copper sulfide compounds have been intensively studied as potential thermoelectric materials due to their high dimensionless figure of merit ZT values. They have a unique phonon-liquid electron-crystal model that helps to achieve high thermoelectric performance. Many methods, such as melting and ball-milling, have been adopted to synthesize this copper sulfide compound, but they both use expensive starting materials with high purity. Here, we develop a simple chemical precipitation approach to synthesize copper sulfide materials through low-cost analytically pure compounds as the starting materials. A high ZT value of 0.93 at 800 K was obtained from the samples annealed at 1273 K. Its power factor is around 8.0 μW cm−1 K−2 that is comparable to the highest record reported by traditional methods. But, the synthesis here has been greatly simplified with reduced cost, which will be of great benefit to the potential mass production of thermoelectric devices. Furthermore, this method can be applied to the synthesis of other sulfur compound thermoelectric materials.

ZrCoSb1−xSnx (x = 0, 0.1, 0.2, 0.3, 0.35) half-Heusler (HH) samples were prepared by arc melting, ball milling and then hot-pressing. X-ray diffraction analysis results showed that all samples were crystallized in a HH phase. Thermoelectric (TE) properties of ZrCoSb1−xSnx were measured from room temperature (RT) to 973 K. The Seebeck coefficient changed from negative to positive after substituting Sb with Sn, indicating the occurrence of conduction type transformation in ZrCoSb-based HH compounds. At the same time, the Seebeck coefficient decreased with increasing Sn substitution, and the electrical conductivity increased obviously with Sn addition when x ≤ 0.3. The lattice thermal conductivity of Sn-substituted samples was reduced dramatically because of the stronger phonon scattering by the strain field fluctuation induced by Sn replacement of Sb. Finally, as a result of the Sn substitution, a peak ZT of 0.52 was reached at 973 K in the ZrCoSb0.7Sn0.3 sample.

•Nitrogen-doped graphene were prepared through electrochemical exfoliation.•The nitrogen-doped graphene demonstrates high N-doping levels of 6.05 atom%.•This nitrogen-doped graphene show enhanced supercapacitor behaviors.Electrochemically anodic exfoliation of graphite has been developed for nitrogen-doped few-layer graphene sheets (N-FLGS), demonstrating high N-doping levels of 6.05 atom%. The process for the preparation of N-FLGS is involved with the intercalation of glycine anions H2NCH2COO− into the graphite layers, electro-polymerization of large electro-oxidation products H2NCH2CONHCH2−, and in situ N-doping in the graphite layer. Transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy were employed to characterize the structure and properties of the N-FLGS. The as-fabricated N-FLGS utilized as electrode materials for supercapacitor exhibit enhanced electrochemical performance, including excellent cycling stability (the capacitance ratios after 10 000 cycles is 96.1%) and a remarkable rate capability (184.5 F g−1 at 1 A g−1, 132.7 F g−1 at 50 A g−1).Nitrogen-doped few-layer graphene sheets prepared through electrochemical exfoliation show excellent cycling stability and remarkable rate capability when utilized in supercapacitor.

•A hardly achieved Al10O3N8 based phosphor was prepared successfully by some special route for the first time.•It is UV and VUV luminescence properties were researched carefully.•Si–N substitution for Al–O bond was adopted to increase the luminescence intensity and the mechanism was discussed.A novel Al10O3N8:Eu2+ phosphor was prepared successfully by a mechanochemical activation route. With the help of high-energy ball milling, the starting materials were mostly transformed into an amorphous phase, which significantly promotes the synthesis of Al10O3N8 phase at a relatively moderate reaction condition. Al10O3N8:Eu2+ phosphor showed a broad blue emission band under ultraviolet-light excitation and small thermal quenching. Additionally, it was found that Al10O3N8:Eu2+ phosphor showed a strong blue emission under 147 nm excitation and shorter decay time compared with BAM:Eu2+ phosphor, making it a potential phosphor used in plasma display panels. Si–N doping was performed to further increase the luminescence intensity of Al10O3N8:Eu2+ phosphor and the related mechanism was discussed. Prospectively, it was feasible to apply the synthesis approach to other hardly achieved materials.

The optical properties of e-shape plasmonic nanocavities have been studied. Due to the destructive interference of the quadrupole resonance of the c-shape nanoring with the overlapping dipolar resonance of the nanorod, a tunable Fano resonance within a wide range of spectra from visible light to mid-infrared (mid-IR) spectrum have been observed. The spectral positions and modulation depths of the Fano resonances can be tuned with different geometry parameters of nanocavities, and the performance (modulation depth of spectra and near-field enhancement) of e-shape plasmonic nanocavities can be further improved by optimization of the nanocavity’ radiation characteristics using a dielectric layer (SiO2). Furthermore, capacitive coupling between c-shape nanoring and nanorod antenna was found to be asymmetric, in which Fano resonance can be modulated to symmetric/antisymmetric quadrupole–dipole by moving the nanorod in the positive/negative direction of the x axis. This work opens up new opportunities for engineering spectral features and optimizing performance of a broad range of plasmonics devices.