Mesoporous silica nanoparticles (MSN) with tunable pore size have been proved to be excellent potential in molecular-related applications. Herein, in this study, we designed to synthesize MSN with tunable pore size by varying the n-octadecyltrimethoxysilane (C18TMS)/tetraethylorthosilicate (TEOS) molar ratio or the ethanol (EtOH)/H2O volume ratio in a water-ethanol-ammonia system, where C18TMS acted as structure-directing agent, TEOS as silica source, ammonia as catalyst, EtOH and H2O as solvents. The as-obtained MSN were characterized by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption analysis. The results showed that the as-synthesized MSN possessed spherical morphology with diameter ranging from 100 to 200 nm, and the pore size of MSN could be easily tailored from 2.4 to 6.5 nm simply by varying the C18TMS/TEOS molar ratio from 0.32 to 0.74 and the EtOH/H2O volume ratio from 3.6 to 7.5. Meanwhile, the pore volume also could be adjusted from 0.6 to 1.0 cm3/g by this strategy. These results suggested that our strategy could effectively enlarge and adjust the mesopores of the MSN. We supposed our approach may provide a platform of nanotechnology for preparation of porous silica materials with adjustable mesopores which would be great potential in practical applications where different sizes of molecules were involved.

•The magnetic and electronic properties of Al or P doped armchair silicene nanoribbons.•The magnetic moment and band gap are dependent on the ribbon width.•The band gap oscillates with a period of three with the ribbon width increasing.Using the first-principles calculations, we investigate the geometric structure, electronic and magnetic properties of armchair silicene nanoribbons (ASiNRs) doped with aluminum (Al) or phosphorus (P) atoms. Total energy analysis shows that both Al and P atoms are preferentially doping at the edge site of ASiNRs. And the magnetism can be found in both Al and P doped systems. For Al doped ASiNRs, we find that the magnetic moment and band gap are dependent on the ribbon width. While for P doped ASiNRs, the magnetic moment always keeps 1μB and is independent of the ribbon width, meanwhile the band gap oscillates with a period of three with the ribbon width increasing. Our results present a new avenue for band engineering of SiNRs and benefit for the designing of silicone-based nano-spin-devices in nanoelectronics.

•Charge mobility and half-metallicity in two dimensional metal coordination PP sheets.•All 2D metal coordination PP sheets show n-type semiconducting.•The hole mobility in all systems show anisotropy in-plane.We have investigated the electronic structures and carrier mobility of two dimensional (2D) metal coordination polyporphyrin (PP) sheets using density functional theory combined with Boltzmann transport method with relaxation time approximation. Two families of metal coordination atoms are studied: 1) 3d-transition metals (TM) Fe and Co; and 2) nonferrous metals (NM) Li and Zn. It is shown that 2H-PP, 2Li-PP and Zn-PP are direct gap semiconductors, while Fe-PP and Co-PP are spin-splitting and behave like half-metallic. Moreover, the charge mobilities have been carried out under periodic boundary conditions for infinite 2D PP systems, and found that the electron mobility is higher than that of the hole's, which indicating the n-type semiconducting characteristic. Furthermore, we also found the hole mobility in all systems show anisotropy in-plane.Download high-res image (389KB)Download full-size image

•MSN were designed as carriers for water-insoluble PTX.•The solubility of PTX was highly improved after loading into MSN.•Drug loading capacity increased as the polar parameter of solvent decreased.•Drug loading content increased as the drug/carrier mass ratio increased.•The cytotoxicity of PTX loaded MSN increased as PTX concentration increased.In this study, paclitaxel (PTX), a typical chemotherapeutic agent with poor water-solubility, was selected as the model drug to evaluate the feasibility of mesoporous silica nanoparticles (MSN) to load a hydrophobic drug in different solvents. A sol-gel method was used to synthesize MSN. Drug loading was carried out in three different solvents: dichloromethane, ethanol and dimethyl sulfoxide (DMSO) via a solvent evaporation method, and their effects on drug loading were examined. We further studied the effects of drug loading period and mass ratio of drug to carrier on drug loading capacity of MSN, as well as the in vitro drug release was analyzed. Moreover, the cytotoxic effect of PTX loaded MSN on liver carcinoma (HepG2) cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The related materials were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), dynamic light scattering (DLS), fourier transform infrared spectrometer (FTIR), small-angle x-ray scattering (SAXS), wide-angle x-ray diffraction (XRD) and N2 adsorption-desorption analyses. The results demonstrated a highly improved solubility of PTX by using MSN as drug carriers compared to free PTX. In addition, drug loading content increased as the solvent polarity parameter decreased or the drug/carrier mass ratio increased. Compared with the blank MSN, the PTX loaded MSN could produce a significant cytotoxicity on HepG2 cells. Our results indicated that MSN could be very potential drug delivery carriers for poorly water soluble drugs.Download high-res image (218KB)Download full-size image

Blue phosphorus is a new graphene-like material which has already been proven thermostable in theory, and the synthesis of it on experiment can also be expected. Here, we have investigated the electronic structures and carrier mobilities of armchair and zigzag monolayer blue phosphorus nanoribbons (PNRs) and nanotubes (PNTs) using density functional theory combined with Boltzmann transport method with relaxation time approximation. It is found that both PNRs and PNTs are indirect-gap semiconductors with a considerable energy gap. The numerical calculation results indicate that the armchair PNTs, zigzag PNTs, and armchair PNRs have the characteristics of p-type semiconductors in electrical conduction, because the hole mobility is over 1 order larger than the electron mobility. However, the electron mobility is greater than the hole mobility in zigzag PNRs. Owing to the existing px orbitals (in-plane and along ribbon direction), which are very sensitive to the atomic structure strain, the band edges will be significantly changed under strain which results in a linear decrease of the gap of PNRs and PNTs with deformation aggravation. The charge mobilities can also be effectively regulated by the strain.

Using density functional theory coupled to the Boltzmann transport equation with relaxation time approximation, we study the electronic structure and carrier mobility of graphene-like hexagonal boron phosphide (h-BP) monolayer and H-terminated armchair boron phosphide nanoribbons (ABPNRs). Our results show that the carrier mobility can reach over 104 cm2 V–1 s–1 for electron and 5 × 103 cm2 V–1 s–1 for hole in monolayer sheet. The carrier mobility in the ABPNRs is in the range of 103 to 104 cm2 V–1 s–1, and we find that the width of nanoribbon plays an important role in tuning the polarity of the carrier transport, which exhibits a distinct 3p (p is a positive integer) alternating behavior. The staggering oscillating behavior of mobility should be attributed to different bond characteristics of the edge states in the ABPNRs. Moreover, the H-terminated zigzag boron phosphide nanoribbons (ZBPNRs) have the characteristics of p-type semiconductors in electrical conduction, and the carrier mobility is increased with the width of the nanoribbons and no alternating size-dependent carrier polarity is found. The high carrier mobility and adjustable polarity of transport suggest that h-BP is a promising candidate material for application in future nanoelectronic devices.

Using the nonequilibrium Green’s function method combined with spin-polarized density functional theory, we investigate the spin-resolved electronic transport properties of devices made of poly-(terphenylene-butadiynylene) (PTB) between two symmetric ferromagnetic zigzag graphene nanoribbon (ZGNR) electrodes. The bipolar spin filtering effect, rectifying behavior, and negative differential resistance have been found. More interestingly, an on/off ratio in the order of 107 is also predicted by changing the angle between the PTB and ZGNR electrode planes. Further analyses show that the matching of the electronic wave functions among both electrodes and PTB plays a key role in the multi-functional PTB based device. And the coupling between the alkyne triple bond and the phenyl rings of PTB is critical to the value of the spin-resolved current and the on/off ratio. These phenomena suggest that the proposed PTB based devices have potential utilization in molecular spin diodes and molecular switches.

We have investigated the electronic structure and carrier mobility of monolayer black phosphorus nanoribbons (BPNRs) using density functional theory combined with Boltzmann transport method with relaxation time approximation. It is shown that the calculated ultrahigh electron mobility can even reach the order of 103 to 107 cm2 V–1 s–1 at room temperature. Owing to the electron mobility being higher than the hole mobility, armchair and diagonal BPNRs behave like n-type semiconductors. Comparing with the bare BPNRs, the difference between the hole and electronic mobilities can be enhanced in ribbons with the edges terminated by H atoms. Moreover, because the hole mobility is about two orders of magnitude larger than the electron mobility, zigzag BPNRs with H termination behave like p-type semiconductors. Our results indicate that BPNRs can be considered as a new kind of nanomaterial for applications in optoelectronics, nanoelectronic devices owing to the intrinsic band gap and ultrahigh charge mobility.

Using the density functional theory (DFT) and the nonequilibrium Green's function (NEGF) method, we study the electronic structures and transport properties of zigzag boron–nitrogen–carbon nanoribbons (BNCNRs), which are constructed by the substructures of the B–N nanoribbons (BNNRs) and graphene nanoribbons (GNRs). The different position relationships (center or edge) of the BNNRs and GNRs, and the different edge patterns of the BNCNRs have been considered systematically. We found the electronic structures and transport properties of BNCNRs are significantly affected. The metallic and semiconductive properties of the BNCNRs can be modulated by the different combinations of the BNNRs and GNRs. And our results suggest BNCNRs would have potential applications in graphene-based nano-devices.

•The spin-dependent electronic transport properties of zigzag silicene nanoribbons.•Effects of the asymmetric edge hydrogenation on spin-dependent transport.•Bipolar spin-filtering, rectifying and giant magnetoresistance effects can be observed.Using the nonequilibrium Green's function method and the spin-polarized density functional theory, the spin-dependent electronic transport properties of zigzag silicene nanoribbons (ZSiNRs) with asymmetric edge hydrogenation have been studied. The results show that there exists nearly 100% bipolar spin-filtering behavior in the ZSiNR-based devices with antiparallel spin configuration. Moreover, rectifying behavior and giant magnetoresistance are found in the devices. Our calculation suggests ZSiNRs with asymmetric edge hydrogenation as a promising candidate material for spintronics.

The fluorination of dithiophene-tetrathiafulvalent (DT-TTF) was investigated by using the density functional theory combined with nonequilibrium Green's function method. It is demonstrated that fluorination can modify the electronic transport properties of DT-TTF. Negative differential resistance can be observed within a certain bias voltage range in 4FDT-TTF.Highlights► Fluorination effects on the electronic transport in TTF molecular junction. ► F-substitution can modify the electronic transport properties of DT-TTF. ► NDR can be observed within a certain bias voltage range in 4FDT-TTF.

The fluorination of dithiophene-tetrathiafulvalent (DT-TTF) was investigated by using the density functional theory combined with nonequilibrium Green's function method. It is demonstrated that fluorination can modify the electronic transport properties of DT-TTF. Negative differential resistance can be observed within a certain bias voltage range in 4FDT-TTF.Highlights► Fluorination effects on the electronic transport in TTF molecular junction. ► F-substitution can modify the electronic transport properties of DT-TTF. ► NDR can be observed within a certain bias voltage range in 4FDT-TTF.

Applying nonequilibrium Green’s functions in combination with the density functional theory, we investigated the effect of amino and hydroxyl groups on the transport property of the carbon atomic chains. The results show the conductance oscillation with the length and the parity of the carbon atomic chains, and the electronic transport properties can be modulated by the sites of amino and hydroxyl groups. And also, the negative differential resistance behaviors can be observed clearly. These phenomena may originate from the interaction of side groups with the carbon atomic chains and the change in coupling degree between the molecular orbitals and electrode states.highlights► The transport property of the carbon atomic chains can be modulated by amino and hydroxyl groups. ► The conductance oscillation effect with the length and the parity of the carbon atomic chains appears in the perfect systems. ► The negative differential resistance behaviors can be observed clearly in some carbon atomic chains.