Electrochemical conversion of H2O/CO2 to fuel in a proton-conducting solid oxide electrolyser

► CO2 was electrochemically reduced into CO in H+-type solid oxide electrolysers. ► LSCM-based oxygen electrode shows excellent performance for H2O electrolysis. ► Reoxidation of LSCM is the main process at low voltage during electrolysis. ► Electrochemical oxidation of H2O is main process at high voltage in electrolysis.