Facet-Dependent Electronic Metal-Support Interaction on Ni/CeO₂ Catalysts for the Water-Gas Shift Reaction

Nickel-based catalysts have gained significant attention for their applications in hydrogen production and purification via water-gas shift (WGS) reaction. The nickel-oxides interaction is pivotal in optimizing the catalytic performance of WGS reaction. Herein, the well-defined Ni/CeO₂ catalysts with specific rodlike and polyhedral morphologies were used to investigate the facet-dependent catalytic behaviors in WGS reaction. The structural properties were determined using multiple techniques, indicating that Ni/CeO₂(110) and Ni/CeO₂(111) model catalysts were successfully constructed with similar textural features except for the exposed facets. Ni/CeO₂(111) exhibited higher intrinsic activity than Ni/CeO₂(110) for WGS reaction (73.7 vs 61 h^-1). TPSR and kinetic data suggested that Ni/CeO₂ catalyzed WGS reaction via redox pathway with the CO adsorption/activation as the rate-limiting step. XPS and CO-DRIFTS results revealed that Ni/CeO₂(111) possessed stronger electronic metal-support interaction (EMSI) and superior reducibility than Ni/CeO₂(110), resulting in the enhanced WGS activity. DFT calculations further elucidated the facet-dependent EMSI effect on CO and H₂O adsorption/activation, revealing that Ni/CeO₂(111) exhibits stronger CO adsorption and a lower reaction energy barrier (0.9 eV) than Ni/CeO₂(110) (1.56 eV) with comparable H₂O dissociation barriers (0.39 vs 0.61 eV) on both surfaces. This work highlights the facet-dependent EMSI as an efficient strategy to optimize the Ni-catalyzed WGS reaction.