Water Adsorption and Dissociation on Ceria-Supported Single-Atom Catalysts: A First-Principles DFT+U Investigation

Single-atom catalysts have attracted wide attention owing to their extremely high atom efficiency and activities. In this paper, we applied density functional theory with the inclusion of the on-site Coulomb interaction (DFT+U) to investigate water adsorption and dissociation on clean CeO₂ (111) surfaces and single transition metal atoms (STMAs) adsorbed on the CeO₂ (111) surface. It is found that the most stable water configuration is molecular adsorption on the clean CeO₂ (111) surface and dissociative adsorption on STMA/CeO₂ (111) surfaces, respectively. In addition, our results indicate that the more the electrons that transfer from STMA to the ceria substrate, the stronger the binding energies between the STMA and ceria surfaces. A linear relationship is identified between the water dissociation barriers and the d band centers of STMA, known as the generalized Brønsted-Evans-Polanyi principle. By combining the oxygen spillovers, single-atom dispersion stabilities, and water dissociation barriers, Zn, Cr, and V are identified as potential candidates for the future design of ceria-supported single-atom catalysts for reactions in which the dissociation of water plays an important role, such as the water-gas shift reaction.