High-Temperature Electrochemical Heat Pump Using a Water Gas Shift Reaction. Electrochemical Reduction of CO2 to CO

The electrochemical reduction of CO2 to CO, which is considered to be the key reaction in a new electrochemical heat pump using the water gas shift reaction, was theoretically and experimentally investigated. Thermochemical predictions show that CO2 can be reduced to CO below −0.8 V at 973 K. It was found that the overpotential of the electrochemical reduction of CO2 to CO on a gold electrode was about 0.3 V at 0.01 mA cm−2. Below −1.4 V, in the range where carbon deposition took place, CO could be produced by a chemical reaction between CO2 and carbon. X-ray diffraction showed that the deposited carbon was not amorphous, but graphitized carbon.