Effect of CaCO3 addition on the electrochemical generation of syngas from CO2/H2O in molten salts

A novel green method was presented for the simultaneous synthesis of syngas, a mixture of CO and H2, via the co-electrolysis of CO2/H2O using an established eutectic-salt electrolyte. Optimum electrolysis was carried out at 2.2 V using a two-electrode system composed of a coiled Fe cathode and a coiled Ni anode in eutectic Li1.07Na0.75Ca0.045CO3/0.15LiOH. The molar ratio of H2/CO was finely tuned from 1.96 to 7.97 by controlling the amount of CaCO3. The optimized current efficiency, ∼92%, was acquired by 14.28 wt% CaCO3 addition. Moreover, the relatively low operating temperature of 600 °C was beneficial for practical applications compared to previously reported temperatures in excess of 800 °C, providing a feasible basis for syngas production via electrochemical synthesis. In this manner, CO2/H2O was synergistically converted into valuable chemicals, allowing the CO2 to be utilized efficiently for the conversion and storage of electricity to chemical energy.