The Role of Interfacial Water in CO2 Electrolysis over Ni‐N‐C Catalyst in a Membrane Electrode Assembly Electrolyzer

Abstract

AbstractCO2 electrolysis is a promising route for achieving net‐zero emission through decarbonization. To realize CO2 electrolysis toward practical application, beyond catalyst structures, it is also critical to rationally manipulate catalyst microenvironments such as the water at the electrode/electrolyte interface. Here, the role of interfacial water in CO2 electrolysis over Ni‐N‐C catalyst modified with different polymers is investigated. Benefiting from a hydrophilic electrode/electrolyte interface, the Ni‐N‐C catalyst modified with quaternary ammonia poly(N‐methyl‐piperidine‐co‐p‐terphenyl) shows a Faradaic efficiency of 95% and a partial current density of 665 mA cm−2 for CO production in an alkaline membrane electrode assembly electrolyzer. A scale‐up demonstration using a 100 cm2 electrolyzer achieves a CO production rate of 514 mL min−1 at a current of 80 A. In‐situ microscopy and spectroscopy measurements indicate that the hydrophilic interface significantly promotes the formation of the *COOH intermediate, rationalizing the high CO2 electrolysis performance.