Mechanism Explorationof the Water–Gas ShiftReaction on Cu₄/CeO₂(110) under Realistic ReactionTemperatures

The dynamic evolution of catalysts has a significant impact on the catalytic activity. Herein, we report the dynamic structure of Cu₄/CeO₂(110) at real water–gas shift reaction (WGSR) reaction temperatures and its influence on the WGSR activity in terms of both ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculation. At the reaction temperature (523 K) or catalyst preparation temperature (773 K), reverse spillover of lattice oxygen atoms was observed at the Ce–Cu interface, leaving the corresponding oxygen vacancy (O_V) by AIMD, wherein the interfacial spillover oxygen atoms (O_sp) were proved to be the result of the high active surface of CeO₂(110) and have the function of providing structure support, promoting metal–support interaction (MSI), and inducing steric effect to facilitate H₂O adsorption and COOH formation. Moreover, the charge analysis revealed the MSI trend of Cu₄/CeO₂(110), following the order of 773 K > 523 K > 0 K (i.e., standard DFT-optimized result). Microkinetic modeling showed the catalytic superiority of the 523 K model, followed by 0 K, indicating that MSI should be adjusted to a moderate level. Instead, when the cluster is passivated or shows a low adsorption strength, the active center is transferred to the Cu–O_V–Ce interface site. Interestingly, we found that the 773 K model would promote its activity drastically through O_sp hydroxylation, which would improve the activity of the cluster and avoid water decomposition at the O_sp site, further elevating the production. This work highlights the role of moderate MSI and alternative active centers of the interface in WGSR on supported catalysts. It provides new insights into catalyst design and mechanism exploration for WGSR.