Facet-Oriented Assembly of Mo:BiVO4 and Rh:SrTiO3 Particles: Integration of p–n Conjugated Photo-electrochemical System in a Particle Applied to Photocatalytic Overall Water Splitting

Photo-electrochemical (PEC) and photocatalytic (PC) water splitting are promising solutions to achieve solar-powered hydrogen production. In the present work, to integrate the merits of PEC and PC techniques, a p–n conjugated two-electrode water-splitting system was miniaturized into one particle (denoted as electrode particle) for PC reactions. Specifically, a p-type Rh-doped strontium titanate (Rh:SrTiO3) photocathode material was selectively deposited on the electron-accumulated facet of a particulate n-type Mo-doped bismuth vanadate (Mo:BiVO4) photoanode with inserting a partly oxidized In@InOx interlayer as a grain binder and charge conductor. The photoexcited charge migration and accumulation were visualized through light-assisted Kelvin probe force microscopy. Benefited from efficient interfacial charge transfer and effective surface modification, visible light-driven PC overall water splitting into H2 and O2 was achieved over the prepared Mo:BiVO4/In@InOx/Rh:SrTiO3 electrode particle with an intense-light stability up to 40 h, an ambient pressure endurability from 5 to 95 kPa, and a solar-to-hydrogen energy conversion efficiency of 1.2 × 10–2%. This work develops a strategy of designing an efficient composite photocatalyst for PC overall water splitting and provides insights toward the enhancement of charge transfer efficiency across hetero-semiconductors.