Enhancement of Plasmon‐Induced Photoelectrocatalytic Water Oxidation over Au/TiO2 with Lithium Intercalation

Plasmon‐induced chemical reaction is an emerging field but its development faces huge challenges because of low quantum efficiency. Herein, we report that the solar energy conversion efficiency of Au/TiO2 in plasmon‐induced water oxidation is greatly enhanced by intercalating Li+ into TiO2. An incident photon‐to‐current efficiency as high as 2.0 %@520 nm is achieved by Au/Li0.2TiO2 in photoelectrocatalytic water oxidation, realizing a 33‐fold enhancement in photocurrent density compared with Au/TiO2. The superior photoelectrocatalytic performance is mainly ascribed to the enhanced electric conductivity and higher catalytic activity of Li0.2TiO2. Furthermore, the ultrafast transient absorption spectroscopy suggests that lithium intercalation into TiO2 could change the dynamics of hot electron relaxation in Au nanoparticles. This work demonstrates that intercalation of alkaline ions into semiconductors can promote the charge separation efficiency of the plasmonic effect of Au/TiO2. Low quantum efficiency is a bottleneck for the development of the surface plasmon resonance effect in solar energy conversion. The enhanced electroconductivity and surface catalytic ability of TiO2 after Li+ intercalation can help to achieve highly efficient hot electrons collection and hot holes usage in Au/Li0.2TiO2. Au/Li0.2TiO2’s quantum efficiency of plasmon‐induced water oxidation is greatly increased to 2 % compared to 0.03 % for Au/TiO2.