Interfacial Anchoring Ultrafine CuO _<i>x</i> Nanoparticles on CeO ₂ via Coordination Chemistry to Stabilize Cu ⁺ -O _v -Ce ⁴⁺ Active Sites for CO Preferential Oxidation

The development of ultrafine metal oxide nanoparticles anchored on reducible oxide supports with precisely engineered interfacial active sites has emerged as a critical frontier in heterogeneous catalysis. However, conventional synthesis strategies struggle to reconcile high loading with ultrafine dispersion, often leading to nanoparticle aggregation and compromised stability. Herein, we present a coordination chemistry-driven strategy integrating the hard-soft acid-base principle with a water-etching process to synthesize ultrafine CuO_<i>x</i> nanoparticles anchored on CeO₂. By exploiting the differential coordination affinities of Ce³⁺ and Cu²⁺ with carboxyl ligands in a bimetallic BTC precursor, selective segregation during solvothermal synthesis was achieved. Ce³⁺ formed a stable framework with carboxyl groups, while Cu²⁺ underwent a hydrolysis-induced migration to surface defect sites. Regulating the Cu²⁺/Ce³⁺ ratio enabled precise control over CuO_<i>x</i> dispersion, interfacial Cu-O-Ce bonding, and local structure. The optimized catalyst exhibited a remarkable Cu loading of 21.94% with high dispersion, lattice distortion, and enhanced metal-support interactions. Notably, the designed catalyst demonstrated exceptional stability under H₂-rich streams, which achieved a CO conversion enhancement from 67.4 to 77.7% over 40 h through the interfacial stabilization of metastable Cu⁺-O_v-Ce⁴⁺ active configurations. Advanced characterization and density functional theory (DFT) calculations revealed that the enhanced interfacial Cu-O-Ce interactions and unsaturated coordinated CuO_<i>x</i> species facilitated electron transfer, oxygen activation, and CO adsorption, synergistically boosting the catalytic performance via the Mars-van Krevelen mechanism. This work establishes a rational coordination chemistry-guided paradigm for designing high-performance catalysts with precisely engineered active sites.