Interfacial perfluorosulfonic acid ionomer stabilizing sputtered Bi catalyst for highly selective and scalable CO2-to-formate electroreduction

Abstract

Ionomers in gas diffusion electrodes can actively tune CO₂-to-formate electroreduction. A thin perfluorosulfonic acid ionomer on sputtered Bi creates an ionically conductive interface, delivering >95% formate FE at 400 mA cm⁻² and 135 h stability on a 25 cm²-active-area device at 100 mA cm⁻², outperforming the polytetrafluoroethylene-modified catalyst in activity and durability.