First-principles Investigation On Electronic And Optical Properties Of Functionalized Graphene Hybrid With Wide Band-gap Semiconductor

Photocatalysis is an attractive technology for solving energy crisis and environmental concerns without relying on fossil fuels and the emission of carbon dioxid.Especially,the wide bandgap semiconductors,has been proven to be a promising photocatalytic material in decomposing organic compounds and water splitting for H2/O2 evolution.However,the rapid recombination for photogenerated electron-hole pairs,narrow light response range,only ultraviolet light can be responded,tarnal restricts its energy conversion efficiency of the incoming solar energy,restricted its practical applications.Recently,functionalized graphene-based nanocomposites have been studied.Via ab initio calculations,the photocatalytic activity was studied for the nanocomposites that functionalized graphene hybrid with large band gap semiconductors.?1?SrTiO₃?STO?,as a promising photocatalyst for decomposing organic pollution and water splitting for H2/O2 evolution,has been coupled with the graphene?GR?sheet to enhance photocatalytic activity.Based on that,the mechanism of the enhanced photocatalytic activity was studied for STO/GR nanocomposites via ab initio calculations.We find,the band gap is reduced,and the absorption edge extending to visible-light region.Also explored the potential photocatalytic activity of STO/reduced graphene oxide?RGO??graphane?GRH??.We figure out that the surface termination layer of the STO?100?surface plays an important role in determining the formation energy,interfacial distance,energy band gap,and optical absorption of that nanocomposites.Moreover,the GR sheet is a sensitizer for STO with a termination layer of TiO2,on the contrary,it is an electron shuttle carrying excited electrons from the STO with a termination layer of SrO.Interestingly,a type ?,staggered band alignment is formed in the interface,thus improving photoexcited charge separation.The negatively charged O atoms in the RGO are considered as an active sites for the photocatalytic reactions,resulting in elevating photocatalytic activity.The calculated results can rationalize the available experimental reports and provide design principles for optimizing the photocatalytic performance of the STO-based composites.?2?Generally,grahene?GR?and functionalized graphene are assumed to be the electron shuttle for improving photocatalytic activity of nanocomposites?such as TiO2/GR?.Nevertheless,it not be universal for all experimental results,which demonstrate for the photocatalytic activity of TiO2/GR is lower than TiO2/reduced graphene oxide?RGO?.Base on that,compared several influential factors:band gap,band alignment near the gap,optical absorption,and active sites to figure out the mechanism for the enhancement of photocatalytic activity of TiO2/RGO?GR?via ab initio calculations.Small energy band gap,type-II band alignment and negatively charged O atoms as active sites are acting as vital factors for the photocatalytic activity of TiO2/RGO better than TiO2/GR,ofering physical interpretation for the related experiment results.Moreover,the enhancement of photocatalytic activity for TiO2/graphane?GRH?was predicted.Results indicate functionalized GR is more suitable than pristine graphene for the improvement of the photocatalytic activity for the TiO2/GR-based nanocomposites.