Selectively Adsorbed Mercaptoethanesulfonic Acid on Au/TiO₂ Enhances the Yield and Selectivity of Photocatalytic Reduction of Carbon Dioxide

Abstract

The photocatalytic reduction of carbon dioxide (CO 2 RR) is of paramount importance in the energy industry and environmental protection. Developing highly efficient catalysts plays a central role in advancing CO 2 RR for practical applications, and a Au/TiO 2 heterostructure has emerged as a prominent photocatalyst in CO 2 RR. However, there is still a need to improve the reaction efficiency and selectivity of this heterostructure to realize its full potential in practical applications. Herein, a significant enhancement in the total gas-production rate on the Au/TiO 2 heterostructure is achieved by selectively adsorbing thiol molecules, specifically mercaptoethanesulfonic acid, onto the gold surface. Remarkably, the selectivity toward carbon monoxide has also improved from 62.3 to 79.3%. Notably, the reaction rate and selectivity are strongly influenced by the choice of thiol molecules, their concentration, and the wavelength of light used for illumination. The improved reaction efficiency and selectivity can be attributed to the promotion of charge transfer at the Au−TiO 2 interface induced by molecular adsorption of thiols. This phenomenon leads to enhanced performance in the photocatalytic CO 2 RR process. Importantly, this work presents a simple, convenient, cost-effective, and controllable strategy to improve the reaction efficiency and selectivity of photocatalytic CO 2 RR on the Au/TiO 2 heterostructure. Furthermore, this strategy holds promise for application in various other heterogeneous photocatalytic systems in the near future.