Co Single Atoms and CoO_x Nanoclusters Anchored on Ce_0.75Zr_0.25O₂ Synergistically Boosts the NO Reduction by CO

Achieving high NO conversion and N₂ selectivity in selective catalytic reduction of NO by CO (CO-SCR) in a wide operating temperature window, particularly in the presence of high O₂ concentration, remains a big challenge. Herein, guided by density functional theory (DFT) calculations, a catalyst is rationally developed with dual active centers consisting of both Co single-atoms (SAs) and CoO_x nanoclusters (NCs) co-anchored on Ce_0.75Zr_0.25O₂ support (CZO), which show above 99.7% NO conversion and 100% N₂ selectivity at 250–400 °C under 5 vol% O₂. DFT calculation and experimental results confirm a strong interaction among Co SAs, CoO_x NCs, and CZO support. Co SAs enhance CO adsorption and accompany the oxygen vacancies (OVs) formation in CZO, while the CoO_x NCs promote both NO conversion to nitrate intermediate and the breakage of the N-O bond at OVs, thus synergistically boosting the N₂ formation.