The Mechanism Studies Of Inorganic Semiconductor Materials In Photo-Electrochemistry

In modern society,various environmental problems caused by using fossil fuels are becoming more and more serious.Therefore,the development and utilization of renewable energy have become urgent issues.In recent years,scientists pay more and more attention on photocatalytic hydrogen evolution reaction,CO2 reduction reaction,lithium/sodium ion battery and other topics,because these methods develop the renewable energy and could be recyclable,which embodies the purpose of sustainable development.In hydrogen evolution reaction,hydrogen is produced by decomposing water;In CO2 reduction reaction,CO2 is reduced to generate CH4 and CH3OH,which are convenient for the storage and transportation;In Li+/Na+-ions battery,the charging and discharging process is realized through the insertion and extraction of Li+/iNa+-ion.However,currently these technologies are not widely used due to the efficiency or cost issues.But with the increasing awareness of safety and sustainable development,it becomes more and more important to find and develop renewable energy materials,which also encourgaes researchers to design and develop renewable energy materials.This dissertation mainly simulated some inorganic semiconductors through Materials Studio and VASP,and predicted their potential application in new energy field:1.The first work is to construct the heterostructures of MoS2 on TiO2 at different angles,and calculated their photocatalytic hydrogen evolution reaction efficiency,the properties of MoS2 on three facets(001),(101)and(010)of TiO2 were also tested.By the optimization of various structures,we proved that when MoS2 is basal-on or edge-on TiO2,the structure is relatively more stable.Especially when MoS2 is edge-on TiO2,the catalytic performace could be significantly improved.This work is of great importance to guide the design of new catalysts using two-dimensional materials.2.The second work is to study the application of CsPbBr3 perovskite in the field of CO2 reduction reaction through doping modification.By screening the structures,adsorption energy and free energy of different doping structures,Co and Fe were selected as the doping elements and their efficiency in the CO2 reduction process was tested.It was found that when CsPbBr3 perovskites were doped with Co and Fe,the band gap reduced from 2.32 eV to 1.79 eV and 1.71 eV respectively,which greatly improved the absorption range of visible light.The free energy △G in the CO2 reduction process was also greatly reduced,especially for the Co doped structure.This work predicted the application of CsPbBr3 perovskite in the CO2 reduction process and provided theoretical guidance for the future experiment.3.The third work is to construct heterostructures through transitional-metal dichalcogenides with several MXenes materials,to study the application potential of these structures in the field of sodium ions batteries.By calculating the cohesive energies of each heterostructure construct through different adsorption sites,the most stable binding mode of each combination was found.By testing the adsorption sites of Na+ions between MoS2 and VS2 with MXenes layers and calculated the capacities of Na+ions on the surface,it is found that only when VS2 construct with O-terminated MXenes can support the adsorption and migration of five layers Na+ ions without structural distortion.Meanwhile,the two structures VS2@Ti2CO2Na5 and VS2@V2CO2Na5 have relatively high Na+ion capacity of 601.44 mAhg-1 and 585.29 mAhg-1 respectively,which shows that the structures of VS2@Ti2CO2 and VS2@V2CO2 have the application potential for sodium ions batteries.