Study on nanostructured zinc oxide-derived electrocatalysts and the effect of halides

Abstract

Electrochemical reduction of CO2 using other renewable energy sources to utilize and convert CO2 gas into fuels is a potential solution to answer the environmental issue caused by the high CO2 atmospheric concentration. Lately, nanostructured Au and Ag metallic catalysts have been developed to have enhanced performances. Zn is another promising metallic catalyst for selective CO production from electroreduction of CO2 that is a cost-effective alternative to noble metals, but relatively less studies are conducted. Herein, we demonstrate that porous nanostructured Zn based catalysts reduced from ZnO can enhance electrochemical activity of CO2 to CO conversion with high efficiency and selectivity, and the significance of the initial activation step in high CO2RR activity. Electrolyte environment during reduction activation step plays a role to enhance the catalyst selectivity and decrease carbon impurity deposit. The more oxidized zinc proportion relates to the enhancement of selective CO production and is obtained when bubbling CO2 gas in reduction activation step [1]. Furthermore, the extensive effects of halides were assessed on porous nanostructured Zn-based catalysts reduced from ZnO in different halide electrolytes from KF to KI, which can enhance electrochemical activity of CO2 to CO conversion with high efficiency and selectivity. Our results revealed that the effect of adsorbed halides with a different coverage on porous Zn-based catalysts during the reaction might change some properties of the porous structures together with the chemical states of Zn-based electrocatalysts, which were critical to the stabilization of the *COOH intermediate resulted from facilitating the charge donation from halide ions to CO2 coupled with the proportion of oxidized zinc components and stable oxygen species, thus, determine the activity for CO2 to CO of electrocatalysts [2].