Function-switchable metal/semiconductor junction enables efficient photocatalytic overall water splitting with selective water oxidation products

A novel metal/semiconductor photocatalyst , Cu nanoparticles (NPs) modified TiO 2 hollow spheres (Cu/TiO 2 ), was designed for efficient photocatalytic overall water splitting (POWS) under both ultraviolet (UV) and visible (Vis) light. This Cu/TiO 2 photocatalyst possesses excellent POWS performance under Vis light at the highest level among the reported TiO 2 -based photocatalysts. Interestingly, the metal/semiconductor junction formed between Cu and TiO 2 enables controlled water-oxidation product selectivity (H 2 O 2 or O 2 ) via different reaction pathways regulated by irradiation wavelengths. Under UV light , the electrons excited in TiO 2 are captured by Cu NPs through the Cu/TiO 2 Schottky interface for H 2 production, with the photoholes in TiO 2 producing H 2 O 2 through a two-electron process; whilst under Vis light, Cu NPs act as plasmon to inject hot electrons to TiO 2 for H 2 production, while O 2 is produced by hot holes on Cu NPs via a four-electron process. This rational design of function-switchable metal/semiconductor junction may be helpful to understand the mechanisms for POWS with desired gas/liquid water-oxidation products.