Electrochemical $CO_2$ reduction using alkaline membrane electrode assembly on various metal electrodes

Abstract

Electrochemical $CO_2$ reduction ($CO_2RR$), which is considered as promising technology to reduce atmospheric $CO_2$ concentration and store renewable energy, is suffer from mass transport problem of $CO_2$ and high cell resistance of conventional liquid phase reactor. Here we report a membrane electrode assembly $CO_2RR$ cell using gas diffusion electrode and anion exchange membrane (AEM) which provide suitable condition for the electrochemical $CO_2$ reduction reaction. $CO_2$ reduction activity of various metals (Pd, Ag, Zn, Cu, Sn, Ru, Pt, Ni) were observed. Among them, Pd, Ag showed high current density (200~ mA $cm^{-2}$ at -3.0 V) and faradaic efficiency (95~ %) toward $CO_2RR$, while system was operated at mild condition (30 °C, 1 atm) and showing low cell resistance ($< 0.150 m\omega$). Furthermore, carbon supported Pd catalyst was tested to maximize usage of precious metal and it showed higher current density, CO selectivity and stability over bare Pd black. Flow rate effect was also investigated in order to achieve highest $CO_2$ conversion.