First Principles Study On Water Splitting On Surface Of Strontium Titanate

Photocatalytic splitting of water into hydrogen and oxygen using a heterogeneous photocatalyst is a potentially clean and renewable solution to convert solar energy into hydrogen fuel.Development of an efficient photocatalyst with both strong visible light absorption and high charge mobility is highly desirable but still remains a great challenge.In this work,we use transition metals atoms M(M= V,Cr,Mn,Zr,Nb and Mo)and nitrogen to codope SrTiO3(001)perovskite surfaces in order to obtain the optimal photocatalytic material with both strong visible light absorption and high charge mobility by density functional theory(DFT)calculations.Results indicate that the V-doped and N-Nb codoped SrTiO3(001)surfaces show smaller band gaps(they are 1.95 and 1.90 eV,respectively)among monodoped and codoped surfaces.Both V-doped and N-Nb codoped SrTiO3(001)surfaces have valence band edge lower than the level of O2/H2O oxidation potential and conduction band edge over than the level of H+/H2 reduction potential.Compared to the undoped SrTiO3(001)surface,the V-doped and N-Nb codoped SrTi03(001)surfaces also exhibit faster charge mobility,which suggests that the V-doped and N-Nb codoped SrTi03(001)surfaces possess the desirable strong visible light absorption and high charge mobility.In addition,we also explore adsorption and decomposition behavior of water on these modified surfaces,and found that V doping can increase the active energy of water decomposition while N-Nb codoping can decrease it,which indicates that N-Nb codoped SrTi03(001)surface not only has the band alignments well positioned for the feasibility of photooxidation and photo-reduction of water,but also significantly reduces the activation energy of water decomposition reaction.This work indicates that N-Nb codoped SrTi03(001)surface is very promising candidate for water splitting in the visible light region,which provides a theoretical foundation for designing new photocatalytic materials.