Manipulating electrochemical CO2 reduction pathway by engineering energy level of Cu/Zn dual-metal single atom catalysts

Dual-metal single atom catalysts (DSACs) demonstrate outstanding catalytic performance in the CO2 reduction reaction. However, the complexity of catalyst structures and interface environments has led to an unclear understanding of the synergistic catalysis mechanism involved. Here, we developed a series of catalysts with atomically dispersed Cu-N4 and Zn-N4 sites on N-doped carbon supports (Cu1-xZnx-NC), which can efficiently reduce CO2 to C2 products by optimizing the Zn loading. Specifically, a remarkable faradaic efficiency of 65 % at -1.1 VRHE for the C2 products on the Cu0.75Zn0.25-NC catalyst has been obtained. Structural characterizations and density functional theory calculations demonstrate that Cu/Zn DSACs synergistically lower the energy barrier of the rate-determining step and facilitate proton transfer kinetics. Among them, Zn atoms activate CO2, while Cu atoms aid in the adsorption and dissociation of intermediates. The electron energy redistribution induced by adjacent Cu-N4 and Zn-N4 site optimizes the 3d orbitals of Cu centers, thereby accelerating and promoting C-C coupling. The energy level optimization of Cu/Zn DSACs results in Cu0.75Zn0.25-NC with a high C2 selectivity and activity, improved kinetics. In summary, these findings provide new insights into the development of highly efficient DSACs and its synergistic catalysis mechanism in CO2 reduction.