Light-assisted synthesis of Au/TiO2 nanoparticles for H2 production by photocatalytic water splitting

A series of Au/TiO₂ photocatalysts was synthesized via the light assistance through the photo-deposition for H₂ production by photocatalytic water splitting using ethanol as the hole scavenger. Effect of solution pH in the range of 3.2–10.0 on the morphology and photocatalytic activity for H₂ production of the obtained Au/TiO₂ photocatalysts was explored. It was found that all Au/TiO₂ photocatalysts prepared in different solution pH exhibited comparable anatase fraction (～0.84–0.85) and crystallite size of TiO₂ (21–22 nm), but showed different quantity of deposited Au nanoparticles (NPs) and other properties, particularly the particle size of the Au NPs. Among all prepared Au/TiO₂ photocatalysts, the Au/TiO₂ (10.0) photocatalyst exhibited the highest photocatalytic activity for H₂ production, owning to its high metallic state and small size of Au NPs. Via this photocatalyst, the maximum H₂ production of 296 μmol (～360 μmol/g?h) was gained at 240 min using the 30 vol% ethanol as the hole scavenger at the photocatalyst loading of 1.33 g/L under the UV light intensity of 0.24 mW/cm² with the quantum efficiency of 61.2% at 254 nm. The loss of the photocatalytic activity of around 20% was observed after the 5th use.