Surface-engineered Cu-substituted CeO2 Nanocatalysts for Low-temperature CO Oxidation

The precise engineering of active sites on heterogeneous catalysts relies on a comprehensive and in-depth understanding of surface structures. Cu-substituted CeO2 catalysts have emerged as promising alternatives to noble metal-based catalysts for CO oxidation. Recent studies have demonstrated correlations between the Cu substitution amount and catalytic activity, however, the underlying atomistic mechanism governing this behavior remains unclear. Herein, we evaluated a series of Cu-substituted CeO2 rod-shaped nanocatalysts, aiming to rationally design a catalyst with a high density of active sites on the surface. The combined spectroscopic investigations, complemented by advanced electron microscopy analysis, revealed a complex interplay between electronic charge carriers localized on both Cu, Ce sites, and the corresponding abundance of oxygen vacancies. Specifically, 10% Cu substitution leads to the highest surface reactivity. First principles Monte Carlo simulations further confirmed the highest surface-available Cu concentration of 10%. Consequently, 10% Cu-substituted CeO2 exhibits superior catalytic performance for low-temperature CO oxidation. The existence of Cu+ species and Cu(0) nanoislands promotes the CO adsorption, while dispersed Cu2+ ions induce lattice distortion and charge imbalance, thus facilitating lattice oxygen mobility. This study reveals novel insights into the influence of heteroatom substitution on catalytically active sites for CeO2-based catalysts.