Junjie Wang’s research while affiliated with Anshun University and other places

Context: Silicon carbide nanowires (SiCNWs) are considered a promising alternative material for application in lithium-ion batteries, with researchers striving to develop new electrode materials that exhibit high capacity and high charge/discharge rate performance. To gain a deeper understanding of the application of SiCNWs in semiconductor material science and energy supply fields, we investigated the effects of nanoscale and surface lithiation on the electrical and mechanical properties of SiCNWs grown along the [111] direction. First-principles calculation was used to study their geometries, electronic structures, and associated electrochemical properties. Herein, we considered SiCNWs with full hydrogen passivation, full lithium passivation, and mixed passivation at different sizes. The formation energy indicates that the stability of SiCNWs increases with the increasing diameter, and the surface-lithiated SiC nanowires (Li-SiCNWs) are found to be energetically stable. The mixed passivated SiCNWs exhibit the properties of indirect band gap with the increase of lithium atoms on the surface, while the fully lithium passivated nanowires exhibit metallic behavior. Charge analysis shows that a portion of the electrons on the lithium atoms are transferred to the surface atoms of the nanowires and electrons prefer to cluster more near the C atoms. Additionally, Li-SiCNWs still have good mechanical resistance during the lithiation process. The stable open-circuit voltage range and theoretical capacity of these SiCNWs indicate their suitability as anode materials. Method: In this study, Materials Studio 8.0 was used to construct the models of the SiCNWs. And all the density functional theory (DFT) calculations were performed by the Vienna ab initio Simulation Package (VASP). The self-consistent field calculations are performed over a Monkhorst-Pack net of 1 × 1 × 6 k-points. The energy convergence criteria for the self-consistent field calculation were set to 10-5 eV/atom with a cutoff energy of 400 eV.

The shape of ceramic particles is one of the factors affecting the properties of metal matrix composites. Exploring the mechanism of ceramic particles affecting the cooling mechanical behavior and microstructure of composites provides a simulation basis for the design of high-performance composites. In this study, molecular dynamics methods are used for investigating the microstructure evolution mechanism in Cu/SiC composites containing SiC particles of different shapes during the rapid solidification process and evaluating the mechanical properties after cooling. The results show that the spherical SiC composites demonstrate the highest degree of local ordering after cooling. The more ordered the formation is of face-centered-cubic and hexagonal-close-packed structures, the better the crystallization is of the final composite and the less the number of stacking faults. Finally, the results of uniaxial tensile in three different directions after solidification showed that the composite containing spherical SiC particles demonstrated the best mechanical properties. The findings of this study provide a reference for understanding the preparation of Cu/SiC composites with different shapes of SiC particles as well as their microstructure and mechanical properties and provide a new idea for the experimental and theoretical research of Cu/SiC metal matrix composites.

The exploration of novel and stable two-dimensional (2D) materials holds considerable significance in the development of optoelectronic devices and photocatalytic water splitting. Herein, MNXY(M/N=Al,Ga,X/Y=N,P,As) monolayers are constructed based on 2D double-layer honeycomb structures. Six stable semiconductor types were screened through first-principles calculations, and their mechanical, electrical, optical, and transport properties as well as their applications in photocatalytic water splitting were investigated. We found that the six stabilized MNXY monolayers had band gaps of 0.846–3.806 eV. The mechanical properties indicate that AlGaN2 has a Young's modulus exceeding 100 N/m, whereas the remaining five monolayers exhibit values below this threshold. The hole carrier mobility of the AlGaN2 monolayer along the armchair direction reaches an ultrahigh value of 3649.21 cm2V−1s−1; thus it has the potential for application in optoelectronic devices. Furthermore, we observed that AlGaP2 monolayers exhibit band-edge potentials spanning the redox potential of water, a considerable difference in electron-hole carrier mobility, strong visible light absorption, and a high solar to hydrogen efficiency (17.51%) in the absence of strain, making them suitable for photocatalytic water splitting. We expect that our results will pave the way forward for material selection for next-generation optoelectronic devices and photocatalysts.