Interfacial Anchoring Ultrafine CuO _x 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 x nanoparticles anchored on CeO 2 . By exploiting the differential coordination affinities of Ce 3+ and Cu 2+ with carboxyl ligands in a bimetallic BTC precursor, selective segregation during solvothermal synthesis was achieved. Ce 3+ formed a stable framework with carboxyl groups, while Cu 2+ underwent a hydrolysis-induced migration to surface defect sites. Regulating the Cu 2+ /Ce 3+ ratio enabled precise control over CuO x 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 H 2 -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 -Ce 4+ active configurations. Advanced characterization and density functional theory (DFT) calculations revealed that the enhanced interfacial Cu–O–Ce interactions and unsaturated coordinated CuO x 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.