Electrodeposited Zn Dendrites with Enhanced CO Selectivity for Electrocatalytic CO 2 Reduction

Electrochemical CO 2 reduction is a key reaction for CO 2 conversion to valuable fuels and chemicals. Because of the high stability of the CO 2 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 CO 2 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 CO 2 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.