Morphological Effects of Copper Oxide on Electrochemical Reduction of Carbon Dioxide Catalyzed by Oxide Derived Copper

Abstract

Electrochemical reduction of carbon dioxide to multi-carbon products is a sought-after avenue towards converting environmentally unwanted CO2 to value-added products. The type and quantity of products depend on the nature of the catalysts and electrochemical reaction conditions. In this context, various metals and metal oxides are being explored as electrocatalysts for electrochemical reduction of carbon dioxide, among which copper is the most versatile electrocatalyst that could form multi-carbon product, such as ethylene. Hence, the present work focuses on investigating and understanding the effects of the morphology of CuO on the product selectivity of the oxide derived copper catalysts for electrochemical reduction of CO2. Five different synthesis protocols have been followed, which include hydrothermal and solution-combustion based routes. All protocols lead to the formation of phase pure CuO, but with varied morphology and particle sizes. It was interesting to note that such variations caused significant differences in the type and relative quantities of the products including carbon monoxide, ethylene, formate in a CO2 saturated aqueous 0.1 M KHCO3 medium. Furthermore, the morphology/size could be tuned to suppress the hydrogen evolution reaction, especially at higher applied potentials. The possible origin of these morphological effects was discussed. Accordingly, this work throws some new and valuable insights into the possibility of tuning the product selectivity in electrochemical reduction of CO2 by varying the morphology/size of the oxide precursor. Keywords: Electrochemical CO2 reduction reaction, CuO, morphological effects, ethylene, CO, formate