Tuning the electron structure enables the NiZn alloy for CO2 electroreduction to formate

Formate is an important liquid chemical, which can be produced by electrocatalytic carbon dioxide reduction reaction (CO2RR). Most of the metal catalysts for CO2RR to formate are toxic or noble metals, such as Cd, Hg, Pb and Pd, leading to the environmental pollution or increased production costs. Herein, we develop an environmentally friendly and low-cost NiZn alloy catalyst for CO2RR to formate. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) confirm the alloy structure of the prepared NiZn catalyst. As for a catalyst for CO2RR, the NiZn alloy exhibits the FEHCOO- (Faraday efficiency of HCOO–) of 36 ± 0.7% at − 0.9 V vs. RHE in 0.1 M KHCO3, and remarkable stability for 40,000 s at − 0.8, −0.9, −1.0 and − 1.1 V vs. RHE, respectively. Theoretical calculation results indicate that the NiZn alloy exhibits the middle valence electron structure between the Zn and Ni metal, resulting in the favorable pathway for HCOOH formation but unfavorable for the hydrogen evolution reaction and CO production. The Ultraviolet Photoelectron Spectroscopy results verify the modulated valence electron structure for NiZn alloy as compared to Ni and Zn, consistent with the theoretical calculation results. This work provides new insights into design of alloy catalysts for CO2RR to formate.