Effectively Tuning the Ratio of CO and H₂ into Syngas through CO₂ Electrochemical Reduction over a Wide Potential Range on a ZnO Nanosheet via Ni Doping

Electrochemical CO2 reduction (ECR) into syngas is a promising method to reduce CO2 in the atmosphere. However, balancing the activity of ECR and hydrogen evolution reaction (HER) and controlling the stable CO/H2 ratios in a large potential range for the industrial desired syngas are still challenging. Herein, a low-cost Ni-doped ZnO nanosheet array on a zinc foil is synthesized via a convenient hydrothermal method to produce a controllable ratio of CO/H2 into syngas. Because of the lower impedance and larger electrochemical area, Ni-doped ZnO has a more significant current density. Furthermore, by adjusting the Ni doping content in the ZnO nanosheet, the activity of ECR and HER could be controlled, and the ratio of CO/H2 can be tuned from 0.1 to 4.5 over a wide potential range (−1.2 to −1.8 V vs reversible hydrogen electrode, RHE), surpassing most of the reported work. Such a wide range and stable ratio of CO/H2 in a broad potential range makes it possible to convert CO2 into feedstock for many essential chemical products.