Interface-Controlled Synthesis of Single-Ce and CeOx Catalysts on Copper Oxide Surfaces

Abstract

The rational design of single-atom cerium (single-Ce) catalysts on copper oxides is crucial for understanding structure–activity relationships in Ce-Cu oxide systems. Using scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), we systematically investigated Ce atom deposition on Cu(111) and Cu₂O surfaces under controlled oxygen atmospheres, revealing distinct interfacial behaviors. On Cu(111), Ce atoms readily aggregate into clusters due to weak metal-substrate interactions. In contrast, Cu₂O surfaces stabilize single Ce atoms through strong Ce-O bonding, enabling atomic dispersion at 300 K. By controlling surface structure and Ce coverage, we synthesized stable single-Ce catalysts on three distinct Cu₂O phases: the metastable “5–7” and ordered “44” and “29” superstructures. Thermal annealing studies (480–550 K) demonstrated that single-Ce and CeO_x clusters can dissociate O₂ and promote Cu₂O oxidation, forming a copper oxide phase with ribbon-like structures. XPS analysis showed a decrease in Ce³⁺ concentration upon annealing, correlating with enhanced oxygen activation. These findings establish Cu₂O as a platform for synthesizing and stabilizing single-Ce catalysts, providing mechanistic insights for further catalytic applications.