Cathode reaction mechanism of CO2/H2O co-electrolysis in solid oxide electrolyte cells

Abstract

Cathode reactions inside solid oxide electrolyte cells (SOEC) for co-electrolysis of steam/CO2 mixtures are examined to elucidate their reduction pathway and enable controlling the syngas yield and selectivity. To investigate important products at various loads, cathode reaction products are analyzed by an online mass spectrometer and gas chromatography. It is shown that the electrochemical reaction pathway is substantially different from that of solid oxide fuel cells. The syngas production rate and product selectivity are highly dependent on gas concentrations, flow rates and electrical loads. It is highlighted that the cathode reaction mechanism is critical to optimize the syngas production rate and product selectivity, and hence the design and operation of coelectrolysis SOEC.