Self-assembled S-scheme In2.77S4/K+-doped g-C3N4 photocatalyst with selective O2 reduction pathway for efficient H2O2 production using water and air
The development of an efficient artificial H2O2 photosynthesis system is a challenging work using H2O and O2 as starting materials.Herein,3D In2.77S4 nanoflower precursor was in-situ deposited on K+-doped g-C3N4(KCN)nanosheets using a solvothermal method,then In2.77S4/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H2O2 production rate of 50IS/KCN can reach up to 1.36 mmol g-1 h-1 without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In2.77S4,respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In2.77S4 according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H2O2 production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O2 around the active centers,the energy barriers of O2 protonation and H2O2 desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H2O2 photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.
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