Asymmetric electronic modulation in bridged Cu-O-Ni dual-atom catalysts promoting CO2 electroreduction

Abstract

Atomically precise heteronuclear dual-site configuration provides an effective strategy to overcome the intrinsic activity and selectivity limitations of single-atom systems in electrochemical CO2 reduction (CO2RR). Here, we introduce an oxygen-bridged Cu-O2-Ni dual-atom catalyst supported on N-doped graphene (Cu-O2-Ni-NG) through an ultrafast Joule-heating process. This rapid treatment enables precise formation of heteronuclear Cu-Ni pairs while preventing metal migration, yielding well-defined Cu-O2-Ni active sites. Comprehensive characterizations verify atomic dimer dispersion and strong electronic coupling between the two metal centers through a stable O-bridge. In CO2RR, Cu-O2-Ni-NG exhibits exceptional CO selectivity (>95%), high catalytic activity, and outstanding operational stability, outperforming the corresponding monometallic controls. Operando Raman spectroscopy reveals potential-dependent evolution of *CO and carbonate species, consistent with a CO-dominant reaction pathway. Density functional theory calculations further show that the O-bridged Cu-O2-Ni geometry optimizes *COOH adsorption, enhances interfacial charge transfer, and synergistically tunes the d-band centers of both metals, thereby lowering the rate-determining energy barrier while effectively suppressing the competing hydrogen evolution reaction. This work establishes oxygen-bridged heteronuclear dimers as a highly efficient platform for CO2RR and highlights the critical role of bridge-atom engineering in the rational design of next-generation dual-site electrocatalysts.