Asymmetric electronic modulation in bridged Cu–O2–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 the electrochemical CO₂ reduction reaction (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 characterization studies verify atomic dimer dispersion and strong electronic coupling between the two metal centers through a stable O-bridge. In the 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 the CO₂RR and highlights the critical role of bridge-atom engineering in the rational design of next-generation dual-site electrocatalysts.