Tuning the Selectivity of Electrocatalytic CO₂ Reduction Reaction via Anion-driven Nanostructuring of Copper Electrodeposits

Abstract

Electrochemical CO2 reduction (ECR) to value-added products is one of the potential ways to utilise CO2 as a feedstock, thereby decreasing its level in the atmosphere as it has harmful repercussions on planet earth. Copper (Cu)-nanostructures have demonstrated a great potential to convert CO2 into valuable higher-end hydrocarbons electrochemically, but with poor selectivity. Therefore, novel strategies to tune Cu-based electrocatalysts' activity and selectivity toward multi-carbon products, particularly at low overpotential, are highly desirable. In the present work, we report an atom-economic strategy to tune the physicochemical properties and the electrocatalytic activity of Cu-nanostructures towards ECR. The Cu-nanostructures synthesized via pulse electrodeposition from an electrolyte bath containing Cu-precursor salts with varying anions (viz. acetates, nitrates, sulphates, and chlorides) are investigated for their effect on the physicochemical properties and the ECR performance. The Cu-electrodeposits having cubic morphology, exposed Cu(100) facets, higher Cu+ content and enhanced electrochemical active surface area demonstrated the best ECR performance depicting good selectivity for ethylene formation.