Amino-functionalization enhanced CO2 reduction reaction in pure water

Abstract

The electrochemical reduction of carbon dioxide (CO₂RR) to carbon monoxide represents a cost-effective pathway towards realizing carbon neutrality. To suppress the hydrogen evolution reaction (HER), the presence of alkali cations is critical, which can however lead to precipitate formation on the electrode, adversely impacting the device stability. Employing pure water as the electrolyte in zero-gap CO₂ electrolyzers can address this challenge, albeit at the cost of diminished catalyst performance due to the absence of alkali cations. In this study, we introduce a novel approach by implementing amino modifications on the catalyst surface to mimic the function of alkali metal cations, while simultaneously working in pure water. This modification enhances the adsorption of carbon dioxide and protons, thereby facilitating the CO₂RR while concurrently suppressing the HER. Utilizing this strategy in a zero-gap CO₂ electrolyzer with pure water as the anolyte resulted in an impressive carbon monoxide faradaic efficiency (FE_CO) of 95.5% at a current density of 250 mA cm⁻², while maintaining stability for over 180 hours without any maintenance.