Synergistic Effect of Atomically Dispersed Ni-Zn Pair Sites for Enhanced CO2 Electroreduction.

Dual-atom catalysts have the potential to outperform the well-established single-atom catalysts for the electrochemical conversion of CO2 . However, the lack of understanding regarding the mechanism of this enhanced catalytic process prevents the rational design of high-performance catalysts. Herein, an obvious synergistic effect in atomically dispersed Ni-Zn bimetal sites is observed. In situ characterization combined with density functional theory (DFT) calculations reveals that heteronuclear coordination modifies the d-states of the metal atom, narrowing the gap between the d-band centre (εd ) of the Ni (3d) orbitals and the Fermi energy level (EF ) to strengthen the electronic interaction at the reaction interface, resulting in a lower free energy barrier (ΔG) in the thermodynamic pathway and a reduced activation energy (Ea ) as well as fortified metal-C bonding in the kinetic pathway. Consequently, a CO faradaic efficiency of >90% is obtained across a broad potential window from -0.5 to -1.0 V (vs RHE), reaching a maximum of 99% at -0.8 V, superior to that of the Ni/Zn single-metal sites.