Visible light assisted highly efficient hydrogen production from H2S decomposition by CuGa02 and CuGa_(1_x)InxO2 delafossite oxides bearing nanostructured co-catalysts

摘要

The present communication is the report of our research work on synthesis of new delafossite oxides containing Ga/Ga and In p-block elements,and their visible light driven catalytic activity in solar H2 production from H2S decomposition.CuGaO2 and its indium doped analogue CuGa_(1-x) InxO2 (x = 0.065) delafossite oith NiO and RuO2 co-catalysts loading in nanostructures were prepared by solid state reaction method.These materials possess hexagonal rhombohedral structure (XRD);morphologically CuGaO2 has irregularly-shaped plate like particles while all others have ordered hexagonal rod-like arrangements (FESEM).Co-catalyst deposits of few nm sizes are observable as white spots/patches on the surface of naked xides without/woxide catalysts.Acquiring p-type conductivity from the mixed valence of Cu (+1 and +2) and oxygen deficiency,these catalysts strongly absorb visible light (Eg = 1.85 eV) in a wide wavelength range.They decompose H2S in aqueous 0.5 M KOH solution Under visible light (lambda >= 420 nm) irradiation and generate H2 to the tune of 4300 mu mol/h,giving rise to a high quantum efficiency of 13.6% at 550 nm.The exceedingly higher rate of H2 production appears to result from a combined contribution of chemical nature (p-block elements Ga and In),p-type conductivity and an efficient e~-h+ separation.