Function-oriented Design of Robust Metal Cocatalyst for Photocatalytic Hydrogen Evolution on Metal/Titania Composites
Abstract To realize the rational design of improved catalysts is one of ultimate goals in catalysis, though practical strategies are generally in shortage, especially for the complicated photocatalytic processes. Here, we take the hydrogen evolution reaction (HER) as an example, and introduce a theoretical approach for designing robust metal cocatalysts supported on TiO2, using density functional theory calculations adopting on-site Coulomb correction and/or hybrid functionals. The approach starts with clarifying the individual function of each metal layer of metal/TiO2 composites in photocatalytic HER, covering both the electron transfer and surface catalysis aspects, followed by conducting a function-oriented optimization via exploring competent candidates. With this approach, we successfully determined and verified bimetallic Pt/Rh/TiO2 and Pt/Cu/TiO2 catalysts to be robust substitutes for conventional Pt/TiO2. The right metal type as well as the proper stacking sequence are demonstrated to be the key to boosting the performance. Moreover, we pioneeringly identified the tunneling barrier height as an effective electron transfer descriptor for photocatalytic reactions on metal/oxide catalysts. We believe that this study pushes forward the frontier of photocatalyst design towards higher water splitting efficiency.