Photocatalytic H2O2 production from O2 under visible light irradiation over phosphate ion-coated Pd nanoparticles-supported BiVO4

H2O2 production from O-2 over Pd nanoparticle (NP) co-catalysts-supported BiVO4 was studied. Several deposition methods and conditions (active metal, co-catalyst loading, solution pH) were investigated for catalyst preparation, and the photo-assisted deposition (PAD) of Pd from an aqueous phosphate buffer solution (pH = 7) was found to be optimal, resulting in small and uniform phosphate ion (PO43-)-coated Pd NPs being selectively deposited on the reductive surfaces of the BiVO4. This catalyst exhibited better H2O2 production from O-2 in the presence of methanol (CH3OH) as a hole scavenger under visible light irradiation than that by the catalysts prepared by the other methods and under other PAD conditions. It is surmised that PO43- partially coats smaller Pd NPs with a narrow size distribution on the reductive surfaces of the BiVO4, and that these NPs promote H2O2 generation synergistically by catalyzing the two-electron reduction of O-2 while simultaneously inhibiting the four-electron reduction of O-2 and the two-electron reduction of H2O2 to H2O.