Spatially separated bimetallic cocatalysts on hollow-structured TiO2 for photocatalytic hydrogen generation

Abstract

Efficient charge separation and light harvesting of photocatalysts (e.g., TiO₂) are the key issues to be considered in the design of solar-energy conversion systems. In particular, the charge separation of noble metal-decorated TiO₂ materials could be greatly improved via decreasing the size of noble metal particles (NPs). Furthermore, designing specific morphologies such as hollow structures can improve light harvesting ability. Herein, a hybrid hollow TiO₂ with spatially separated bimetals (Pd@TiO₂@Au) was prepared, which demonstrated enhanced charge separation. By choosing zeolite as the sacrificial substrate, ultrasmall Pd NPs and Au NPs were decorated in the inner and outer shells of hollow TiO₂, respectively. The separated bimetals could pull the photoexcited electrons away from the surface of TiO₂ for more efficient charge separation. The as-prepared Pd@TiO₂@Au catalyst exhibited a superior photocatalytic H₂ evolution rate up to 272.3 μmol h⁻¹, which was higher than most of the TiO₂-based photocatalysts.