Electrochemical Treatment of Au/TiO₂ for Catalysis Improvement in Hydrogen Evolution

Metal–semiconductor heterostructures have been widely used in photocatalytic and electrocatalytic reactions because of their improved charge transfer at the interface. One of the strategies to further improve their catalytic performance is to introduce oxygen vacancies, which may improve the electrical conductivity, active sites, and/or electronic structure of the catalyst surface. Herein, we introduce a simple and convenient method to introduce oxygen vacancies into the heterostructure of gold and titanium oxide (Au/TiO2). Oxygen vacancies are introduced by applying a large negative bias to the Au/TiO2 heterostructures deposited on the electrode. The electrochemically treated sample (referred to as Vec-Au/TiO2) shows an improvement in catalytic performance in the electrocatalytic hydrogen evolution reaction (HER) by 2.46-fold. In addition, an improvement in the photocatalytic HER by 64.6% could also be observed on Vec-Au/TiO2. The catalytic enhancement could be attributed to the improved interfacial charge transfer and catalytically active sites. Moreover, the validity of our strategy has also been demonstrated in other heterostructure-based catalytic systems. Overall, this work demonstrates a simple and effective way to improve the catalytic HER performance of Au/TiO2 heterostructures, and this method can be extended to many other catalytic systems.