Molecularly Designed Cathode for Copper-Benzimidazole-Induced CO2 Reduction to MeOH

Abstract

Conversion of carbon dioxide (CO₂) into value-added products is aimed to develop scalable technologies to promote a circular economy. While the electrochemical reduction of CO₂ to carbon monoxide (CO) and formic acid has advanced significantly, a major challenge remains achieving further reduced and more energy-dense products, such as methanol (MeOH), through sustainable pathways. Herein, we report a molecular electrode capable of direct six-electron reduction of CO₂ to MeOH using water as a proton source with a global Faradaic efficiency (FEG) of 22% and product selectivity of 61% for MeOH. The design consists of an active copper-hydride center surrounded by two closely spaced benzimidazole–hydride units, facilitating the catalytic transfer of three hydrides to produce MeOH. The concurrent formation of formic acid and the absence of formaldehyde suggest that MeOH is generated via a formato pathway. DFT investigations revealed the complete mechanistic pathway, which supports the experimental observations. The morphology and stability of the electrode were evaluated before and after prolonged electrolysis (12 h) experiments using electron microscopic techniques.