Enhancing electrochemical carbon dioxide reduction efficiency through heat-induced metamorphosis of copper nanowires into copper oxide/copper nanotubes with tunable surface

Abstract

Electrochemical CO2 reduction reaction (CO2RR) presents a unique opportunity to convert carbon dioxide (CO2) to value-added products while simultaneously storing renewable energy in the form of chemical energy. However, particle applications of this technology are limited due to the poor efficiency and product selectivity of the existing catalyst. In this study, we demonstrate a facile method for the heat-induced transformation of copper nanowires into CuOx/Cu nanotubes with defect-enriched surfaces. During this transformation, the outward migration of copper results in the formation of tubular structures encased within nanosized oxide grains. Notably, the hydrogen faradaic efficiency (FE) decreases with extended heat treatment, while carbon monoxide (CO) FE increases. As compared to Cu NWs, Cu NTs exhibit lower selectivity towards H2 and single-carbon (C1) products and favor the formation of multi-carbon (C2+) products. Consequently, a 2-fold increase in the single pass CO2 conversion (SPCC) and C2+ half-cell energy efficiency (EEhalf cell) was noted after heat treatment. The Cu NT-4 variant, synthesized under optimized conditions, exhibits the highest FE of 72.1 % for C2+ products at an operating current density (ID) of 500 mA cm−2.