Steering plasmonic hot electrons to realize enhanced full-spectrum photocatalytic hydrogen evolution

Abstract

Integration of surface plasmons into photocatalysis is an intriguing approach to extend the light absorption range over the full solar spectrum. However, the low migration rates and uncertain diffusion directions of plasmonic hot electrons make their photocatalytic efficiency fail to meet expectations. It remains a challenging task to steer the migration of hot electrons and take full advantage of the plasmonic effect to achieve the desired high photocatalytic efficiency. Herein, we have developed an efficient strategy to steer the migration of plasmonic hot electrons through a well-designed hybrid structure that synergizes a “surface heterojunction” with a Schottky junction. The hybrid structure was synthesized by modifying titanium dioxide (TiO2) nanosheets (NSs) with gold (Au) nanoparticles (NPs) as a plasmonic metal and platinum (Pt) NPs as a co-catalyst. The “surface heterojunction” formed between two different crystal facets in the TiO2 NSs can induce the injection of plasmonic hot electrons from Au NPs excited by visible light to TiO2. Meanwhile, the Schottky junction formed between the Pt NPs and TiO2 NSs can force the migration of electrons from TiO2 to Pt NPs instead of flowing to Au NPs, attaining the efficient unidirectional transfer of carriers in the Au–TiO2 system. Plasmonic photocatalysts with this design achieved dramatically enhanced activity in full-spectrum photocatalytic hydrogen production. This work opens a new window to rationally design hybrid structures for full-spectrum photocatalysis.