Plasmon-Mediated Electrochemical Activation of Au/TiO₂ Nanostructure-Based Photoanodes for Enhancing Water Oxidation and Antibiotic Degradation

Plasmonic photocatalysts have been emerging as a promising candidate for solar energy conversion and environmental remediation. However, those metallic plasmonic photocatalysts inevitably suffer from surface reconstruction and corrosion under harsh reaction conditions, leading to a low activity and poor chemical photostability. Herein, we observe a simultaneous improvement of both activity and photostability on Au/TiO2 nanostructure-based photoanodes induced by an in situ plasmon-mediated electrochemical activation (PMEA) treatment under photoelectrochemical (PEC) water oxidation conditions. Detailed PEC studies demonstrate that the PMEA treatment generates electron-rich surface states at Au/TiO2 interfaces, which results in a high interface charge-transfer efficiency of above 80% and boosts water oxidation activity by 100%. The electron-rich surface states further enhance the PEC stability by reducing the excessive charge accumulation at interfaces and preventing the dissolution of Au. The photoanodes are further tested for the degradation of an antibiotic, ciprofloxacin, which exhibited high PEC activity and stability. Our work provides a convenient method for improving the efficiency and chemical photostability of plasmonic photocatalysts.