A facile strategy to fabricate plasmonic Au/TiO2 nano-grass films with overlapping visible light-harvesting structures for H2 production from water

Abstract

TiO2 nano-grass films were facilely fabricated by a glycerol-assisted hydrothermal process with Ti sheet as precursor. Gold nanoparticles (Au NPs) were then deposited on the surface of TiO2 films by a microwave-assisted chemical reduction route. The investigations reveal that grass-shaped nanostructures of anatase TiO2 films exhibit visible light-capturing property, which can enhance the localized surface plasmon resonance (LSPR) of Au NPs due to the overlapping visible light-harvesting nanostructures between TiO2 film and Au NPs, leading to an enhanced LSPR absorption with two peaks around 405 and 530 nm. Besides, fluorescence quenching is observed in the composite, because the recombination of photoexcited electrons and holes is effectively restrained after deposition of Au NPs. The experimental results indicate that Au NPs can facilitate H2 production from photocatalytic water splitting under ultraviolet light or visible light due to its charge transfer and LSPR properties. The overlapping light-harvesting nanostructures play an important role for the enhanced photocatalytic activity under visible light irradiation. The H2 production rate can reach 4.3 μmol cm−2 h−1 over the optimal sample under UV and visible light (λ > 420 nm) irradiations, and the corresponding energy efficiency is about 0.013. In this contribution, TiO2 film with visible light-capturing ability is achieved by self-structure regulation, which provides a simple strategy to develop film-shaped plasmonic photocatalysts with high efficiency for solar energy conversion.