Roles of oxygen vacancies in surface plasmon resonance photoelectrocatalytic water oxidation

The extremely short lifetime of plasmon-induced charges is a huge challenge to surface plasmon resonance photocatalytic water oxidation. Here, we report that increasing oxygen vacancies (VO) in Au/TiO2-x can greatly enhance the external quantum efficiency of plasmon-induced water oxidation from 0.03% to 1.52% at 520 nm. The increased VO can achieve efficient transportation of plasmonic electrons in the conduction band of TiO2-x with enhanced conductivity and can boost the oxygen evolution kinetics of Au/TiO2-x. The dynamics of plasmonic electrons derived from interband transition reveal that holes in the d-band of Au nanoparticles (NPs) can transfer to the defect states near the valence band of TiO2-x, which originate from VO at the interface of Au/TiO2-x. This process could enrich holes at the interface, making it possible to collect multiple holes for water oxidation. The synchronous functions in hole capture and water molecule adsorption enable VO to be efficient catalytic sites for plasmon-induced water oxidation.