Pd/PdO and hydrous RuO2 difunction-modified SiO2@TaON@Ta3N5 nano-photocatalyst for efficient solar overall water splitting

Abstract

A novel Pd/PdO and hydrous RuO2 difunction-modified SiO2@TaON@Ta3N5 core-shell structured nano-photocatalyst was synthesized successfully, which displayed excellent photocatalytic activity for overall water splitting into H2 (473.52 μmol−1·g−1·h−1), about 2.86 times higher than unmodified SiO2@TaON@Ta3N5 (165.74 μmol−1·g−1·h−1), under the visible-light irradiation with the wavelength ≥420 nm, without any sacrificial agent, as well as excellent stability against photocorrosion. The apparent quantum yield (AQY) reaches to 0.253% under irradiation intensity of 12 mW cm−2 at 420 nm. The spatially separated Pd, PdO and RuO2 clusters were decorated on the Ta3N5 surface to construct local multi-heterojunctions, which were confirmed to enhance the light absorption capability, drive efficient separation of charge carriers and directional transfer, and promote surface redox reaction kinetics of HER and OER. The trace modification of metallic Pd clusters and TaN could mainly contribute to the significant decrease in the HER overpotential, while PdO exhibited a stronger contribution than RuO2 for OER catalytic activity. The synergetic mechanism of enhanced photocatalytic overall water splitting for hydrogen production was discussed in detail. Thus the combination of core-shell heterojunction construction and surface difunction modification provides a promising strategy for develop efficient all-in-one photocatalysts for solar overall water splitting.