中央研究院 原子與分子科學研究所

To develop promising dual atom catalysts (DACs) for enhancing valuable C₂₊ products in CO₂ electroreduction (CO₂RR), we need a molecular level understanding of the interaction between reaction intermediates, metal atoms, and substrates. NiMn on graphitic carbon nitride (g-C₃N₄) was experimentally reported to be an efficient CO₂RR catalyst. Here, we studied the origin of its activity. We used integrated crystal orbital Hamiltonian population (ICOHP) analysis along the reaction coordinate of the carbon-carbon (C-C) coupling reaction to understand how the electronic structures of NiMn doped on pristine (NiMn@g-C₃N₄) and N-vacancy graphitic carbon nitride (NiMn@V-g-C₃N₄) affect the reaction. NiMn@V-g-C₃N₄ selectively produces ethanol at low limiting potential -0.55 V and a low kinetic barrier (0.78 eV) for *CO+*CHO→*COCHO. At this step, electron donation from the NiMn in the N-vacancy to the adsorbate is essential. Tricoordinated Ni atom at the vacancy site has a stable oxidation state 0 with a fully filled 3d¹⁰ configuration, while Mn atom takes +2 oxidation state with a half-filled 3d⁵ configuration. ICOHP shows that these electronic configurations result in a moderate binding strength of key intermediates near the Ni while facilitating the flexible change in Mn-C to Mn-O binding for producing *COCHO, thus promoting the formation of ethanol.