Study On The Electronic Structure And Optical Properties Of SrTiO₃ Controlled By Heteroatoms And Two Dimensional Materials

With the development of the social economy,environmental pollution and climate warming have become more and more serious,prompting people to conduct r esearch on new technologies for producing clean and renewable energy.In the 21st century,hydrogen energy is considered to be the most potential energy source for the development of clean energy.Among various hydrogen production methods,the use of sunlight to catalytically decompose water into hydrogen is considered to be the most forward-looking method.In recent years,semiconductor photocatalytic technology has proved to be a potential low-cost,environmentally-friendly and sustainable technology that can solve problems such as chemical synthesis,energy shortages and environmental remediation.In the process of finding efficient catalysts,SrTi O₃ has become a research hotspot in the field of material research because of its strong photochemical corrosion resistance and high photocatalytic activity.In this work,the effects of heteroatom co-doping and two-dimensional composite materials on the electronic structure and optical properties of SrTiO₃ were studied based on first-principles calculations.The specific findings are as follows:?1?Based on the heteroatom-doped SrTiO₃,systematically studied five doping models?Cr@Ti-SrTiO₃,Cr@Sr-SrTiO₃,B@O-SrTiO₃,?Cr@Ti,B@O?-SrTiO₃,?Cr@Sr,B@O?-SrTiO₃?.The synergistic effect of metal Cr doping in different cation positions and nonmetal B codoping is highlighted.The results show that the optical absorption range of SrTiO₃ can be effectively controlled by doping techniques.The band gaps of the two codoping systems?Cr@Sr,B@O?-SrTiO₃ and?Cr@Ti,B@O?-SrTiO₃ are all reduced,but the positions of the energy levels near the Fermi level are different.When Cr is doped at different cation sites,the synergistic effect of the codoping of nonmetal B with metal Cr is different.The photocatalytic activity of SrTi O₃ can be increased by doping mainly due to the combination effect of the narrowing of bandgap and the appearance of intermediate levels.In particular,the?Cr@Sr,B@O?-SrTiO₃ model does not exhibit oxygen vacancies and maintains charge balance,resulting i n a broader light absorption range than other doping models.The results of this study can provide a reasonable explanation for the existing experimental results and help design SrTi O₃-based high-efficiency photocatalytic materials.?2?Taking MoS₂ as an example,we systematic studied the influence of interface interaction on the electronic structure and optical properties of two dimensional material transition metal sulfide/SrTiO₃ composite,and the dual role of MoS₂ as sensitizer and catalyst.Results show that compared with the pure SrTiO₃,MoS₂/SrTiO₃?100?composite material has a small bandgap?1.732 eV?in the visible light absorption range,which extends its absorption spectrum to the visible light region,even the infrared region,and enhances its photocatalytic activity.The MoS₂-modified SrTiO₃?100?composite material forms heterojunctions at the interface,which is beneficial for the separation of photoelectron-hole pairs,and thus improving the photocatalytic activity and stability of SrTi O₃.At the same time,under the light radiation,the electron transition from Mo 4d orbit to SrTi O₃ enhances the reduction activity of the latter,which indicates that the monolayer MoS₂ is an effective sensitizer.Moreover,the inert Mo atoms of the monolayer MoS₂ become the catalytic active sites,making the monolayer MoS₂ become a very active catalyst in the composite catalyst.These results provide a theoretical basis for the development of highly efficient photocatalytic materials based on SrTiO₃ or MoS₂.