A synergistic interaction between isolated Au nanoparticles and oxygen vacancies in an amorphous black TiO2 nanoporous film: toward enhanced photoelectrochemical water splitting

Abstract

Herein, we explore a strategy for significantly enhancing the photoelectrochemical (PEC) water splitting efficiency by means of a synergistic interaction between plasmonic Au nanoparticles (NPs) and oxygen vacancies in an amorphous black TiO₂ (A-B-TiO₂) nanoporous film. The interaction between plasmonic metals and semiconductor substrates was investigated, for the first time, showing that A-B-TiO₂ would be a better support for plasmonic Au NPs than pristine TiO₂ for plasmon-enhanced PEC water splitting. The rationally designed Au@A-B-TiO₂ heterostructure significantly increases the plasmonic effect of Au NPs and consequently improves hot electron injection from Au to A-B-TiO₂, boosting the separation efficiency of hot electron/hole pairs and leading to considerably improved water splitting performance under solar light irradiation. As a proof-of-concept, the Au@A-B-TiO₂ photoelectrode exhibits a photocurrent density of 2.82 mA cm⁻² at 1.23 V vs. RHE under AM 1.5G illumination, which is much higher than those of the state-of-the-art Au–TiO₂ photoelectrodes for PEC water splitting.