Enhanced photocatalytic hydrogen production by loading histidine on TiO2

Abstract Although TiO 2 exhibits excellent photocatalytic properties, its application has been limited owing to rapid e − /h + recombination. Therefore, TiO 2 has failed to reach the desired effect in terms of efficient photocatalytic hydrogen production. In this study, a range of titanium dioxide catalysts loaded with histidine (His) were prepared by an easy dipping method, viz. by treating TiO 2 in His aqueous solutions with different concentrations at ambient temperature. Photocatalytic hydrogen evolution by splitting water was performed on His-modified TiO 2 under 300-W Xe irradiation. His-loaded TiO 2 catalysts exhibited improved photocatalytic performance compared with pristine TiO 2 ; TiO 2 treated in 1 × 10 −3 mol · L −1 His showed the highest photocatalytic H 2 evolution activity (4.77 μ mol g −1 h −1 gm −2 ), which was 3.77 times higher than that of pure TiO 2 . Infrared and XPS analysis showed that His was successfully combined to the TiO 2 surface by hydrogen bonding, constructing a fast channel for interfacial charge transfer. In the photocatalytic process, the photogenerated holes could migrate from the valence band of TiO 2 to the highest occupied molecular orbital of His, which reduced the recombination rate of photogenerated e − /h + pairs, consequently, improved H 2 production efficiency. Importantly, the composite catalyst exhibited no decline in photocatalytic activity over 30 h of operation. This research provides an alternative approach for creating high-efficiency photocatalysts for H 2 production.