d-band center engineering of single Cu atom and atomic Ni clusters for enhancing electrochemical CO reduction to CO.

The rational design of catalysts with atomic dispersion and a deep understanding of the catalytic mechanism is crucial for achieving high performance in CO reduction reaction (CORR). Herein, we present an atomically dispersed electrocatalyst with single Cu atom and atomic Ni clusters supported on N-doped mesoporous hollow carbon sphere (CuNi/NMHCS) for highly efficient CORR. CuNi/NMHCS demonstrates a remarkable CO Faradaic efficiency (FE) exceeding 90% across a potential range of -0.6 to -1.2 V vs. reversible hydrogen electrode (RHE) and achieves its peak FE of 98% at -0.9 V vs. RHE. Theoretical studies reveal that the electron redistribution and modulated electronic structure-notably the positive shift in d-band center of Ni 3d orbital-resulting from the combination of single Cu atom and atomic Ni clusters markedly enhance the CO adsorption, facilitate the formation of *COOH intermediate, and thus promote the CO production activity. This study offers fresh perspectives on fabricating atomically dispersed catalysts with superior CORR performance.