Controlling Mechanism of the Water–Gas Shift Reaction Activity Catalyzed by Au Single Atoms Supported on Multicomponent Oxides

The complicated reaction pathway of the water–gas shift reaction (WGSR) hinders understanding the overall reaction mechanism and extracting the factors to design better performing catalysts. Here, we use density functional theory to study the mechanism of WGSR catalyzed by Au single atoms stabilized at the CeOx–TiO2interfaces on TiO2particles (ACT catalyst). We constructed two energetic landscapes of the WGSR (redox and associative mechanisms), concurrently presenting the H2formation as a rate-determining step. Electronic analysis data showed that the charge state of the oxygen ions participating in WGSR strongly correlates with the oxygen vacancy formation energy (OVF) and hydrogen binding energy (ΔEH), directly scaling the CO oxidation power and the H2production ability. Further expansion toward various Au on oxide–oxide combinations confirmed that the delicate control of metal-oxide-oxide interfaces with optimized local electronic structures expresses the rational design of a WGSR catalyst.