Hybrid CO2 Electroreduction - Associated Anodic Reactions

Abstract

The performance parameter of CO2 electroreduction includes the factor of energy efficiency. The overall energy efficiency for the process includes both the cathode and anode reactions. In aqueous medium, for carrying CO2 electroreduction at cathode, the anodic reaction is majorly oxygen evolution reaction (OER, E0 = +1.23V). Thus, additional useful by-product could be obtained from the CO2 electroreduction process by coupling both processes such that high purity oxygen could also be collected. The electrolytic cell arrangement for obtaining high purity oxygen along with carrying CO2 electroreduction may involve two separate compartments or even two individual electrolytic cells connected by a salt bridge. The issue with continuous ionic replenishing of salt bridge could be taken care by supplying salt electrolyte to the salt bridge or carrying the process with multiple salt bridges.OER is not only energy consuming but its sluggish kinetics lowers the overall efficiency of the process. It is for improving overall efficiency of the process that better catalysts for OER could be employed. Furthermore, the process of oxygen evolution as the counter-reaction of CO2 electroreduction is quite favorable as there is no requirement of any additional or modification in the electrolyte employed for electroreduction of CO2. This advantage of utilizing the same aqueous electrolyte for anodic compartment is focused for achieving enhanced OER and obtaining oxygen as a by-product of CO2 electroreduction process.