Ternary Pt/SnOx/TiO2 photocatalysts for hydrogen production: consequence of Pt sites for synergy of dual co-catalysts

Abstract

A variety of ternary nanoheterostructures composed of Pt nanoparticles (NPs), SnO_x species, and anatase TiO₂ are designed elaborately to explore the effect of interfacial electron transfer on photocatalytic H₂ evolution from a biofuel–water solution. Among numerous factors controlling the H₂ evolution, the significance of Pt sites for the H₂ evolution is highlighted by tuning the loading procedure of Pt NPs and SnO_x species over TiO₂. A synergistic enhancement of H₂ evolution can be achieved over the Pt/SnO_x/TiO₂ heterostructures formed by anchoring Pt NPs at atomically-isolated Sn-oxo sites, whereas the Pt/TiO₂/SnO_x counterparts prepared by grafting single-site Sn-oxo species on Pt/TiO₂ show a marked decrease in the rate of H₂ evolution. The characterization results clearly reveal that the synergy of Pt NPs and SnO_x species originates from the vectorial electron transfer of TiO₂ → SnO_x → Pt occurring on the former, while the latter results from the competitive electron transfer from TiO₂ to SnO_x and to Pt NPs.