Study On Two-Dimensional InSe-Based Heterojunction And Carbon Nitride For Light Absorption And Gas Storage

With the continued development of the economy and the growth of population,problems of energy shortage and gas pollution are becoming more and more serious.The development of new renewable energy sources that can replace traditional fossil fuels and the development of materials that can absorb polluting gases are the two major solutions to environmental pollution problems.Two-dimensional（2D）semiconductor materials have a larger specific surface area,adjustable band edges,and good photovoltaic properties,which have very promising applications in fields such as photocatalysis and gas storage.Firstly,in order to explore photocatalytic materials that can convert solar energy into chemical energy,the performance of several 2D van der Waals（vd W）heterojunction materials in light absorption and charge transfer exciting during photocatalysis is investigated in this paper.Secondly,some polluting gases containing carbon and nitrogen have serious hazards to both the environment and human health.In order to find stable and efficient gas adsorption materials,this paper investigates the carbon-and nitrogen-containing polluting gases adsorption properties of three2D carbon and nitrogen materials,g-C₃N₅,C₂N and C₃N.The main research results are listed as follow:（1）2D vd W heterojunction materials with strong interlayer coupling and short photoexcitation channels are favorable for the formation of novel photogenerated excitons and have better light absorption ability by first-principle and many-body perturbation theory.In Se/β-Sb and In Se/BP expose exceptionally large interlayer transition probability（>500 Debye²）,and can form bright interlayer excitons by direct interlayer photoexcitation.Mo S₂/Mo Se₂,Mo S₂/WSe₂,WS₂/Mo Se₂ and In Se/BP are further investigated,and it was found that strong interlayer coupling as well as short distance photoexcitation channels are two necessary condition to produce strong direct interlayer excitons.（2）Adsorption properties of several small molecules（such as CH₄,CO,CO₂,NH₃,NO and NO₂）on the two-dimensional polar g-C₃N₅ material were investigated,and it was found that different surfaces can achieve NH₃ adsorption and desorption behaviors（-0.38/-0.21 e V）.COHP and AIMD results showed that g-C₃N₅ exhibited good stability for NH₃ storage.（3）Adsorption performance of CH₄,CO,CO₂,NH₃,NO,and NO₂ gases in large-pore C₂N and small-pore C₃N were investigated by simulation calculations.The comparison of adsorption energy results shows that C₃N is more effective than C₂N in gas adsorption,which may due to that C₃N has a narrower band gap than C₂N,resulting in more interactions between C₃N and small gas molecules.In addition,C₃N was found to have selective adsorption of NO₂,as evidenced by lower adsorption energy（-1.05 e V）and significant charge transfer.Therefore,C₃N materials have great potential for NO₂ storage and separation in mixed hazardous gas environments.