Electrodeposited Zn Dendrites with Enhanced CO Selectivity for Electrocatalytic CO2 Reduction

Electrochemical CO2 reduction is a key reaction for CO2 conversion to valuable fuels and chemicals. Because of the high stability of the CO2 molecule, a catalyst is typically required to minimize the energy input and improve reaction rates needed for device level commercialization. In this paper, we report a nanostructured Zn dendrite catalyst that is able to electrochemically reduce CO2 to CO in an aqueous bicarbonate electrolyte with greatly enhanced properties. The catalytic activity is over an order of magnitude higher than that of bulk Zn counterparts, with a CO faradaic efficiency around 3-fold higher. The stability of the Zn electrode under realistic CO2 electrolysis conditions was explored using scanning electron microscopy and in situ/operando X-ray absorption spectroscopy techniques. The results clearly demonstrate that nanostructured and bulk Zn catalysts are structurally stable at potentials more negative than -0.7 V versus RHE, whereas severe chemical oxidation occurs at more positive potentials.