Coupling glycerol oxidation reaction using Ni-Co foam anodes to CO2 electroreduction in gas-phase for continuous co-valorization

Electrocatalytic reduction of CO2 is a promising alternative for storing energy and producing valuable products, such as formic acid/formate. Continuous gas-phase CO2 electroreduction has shown great potential in producing high concentrations of formic acid or formate at the cathode while allowing the oxygen evolution or the hydrogen oxidation reactions to occur at the anode. It is advantageous to use a more relevant oxidation reaction, such as glycerol which is a plentiful by-product of current biodiesel production process. This work successfully manages to couple the glycerol oxidation reaction with continuous gas-phase CO2 electroreduction to formate with the implementation of Ni-Co foam-based anodes. The MEA-electrolyzer developed can achieve significantly high formate concentrations of up to 359 g L-1 with high Faradaic efficiencies of up to 95%, while also producing dihydroxyacetone at a rate of 0.434 mmol m−2 s−1. In comparison with existing literature, this represents an excellent trade-off between relevant figures of merit and can remarkably contribute to a future implementation of this coupled electrochemical system approach at larger scales.The authors gratefully acknowledge financial support through projects PID2019-108136RB-C31, PID2019-108136RB-C32 and PID2019-108136RB-C33, PID2020-112845RB-I00, TED2021–129810B-C21 and PLEC2022-009398 (MCIN/AEI/10.13039/501100011033 and Unión Europea Next GenerationEU/PRTR). This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101118265​