The electrochemical carbon dioxide reduction reaction (CO2RR) provides an alternative route to produce value-added chemicals such as formate, carbon monoxide, ethanol, ethylene etc1. Among these products, formate is one of the most economically viable products of CO2RR2. Several mechanisms are proposed for electrochemical reduction of CO2 to formate. However, thorough investigations of the detailed kinetics and a comparison of the model predictions with experimental results were not found in the literature. Therefore, the primary objective of the proposal is to conduct a thorough mechanistic analysis of electrochemical CO2RR to formate using a planar tin electrode. The use of planar electrodes for commercial applications is constrained by the limited solubility of CO2 in water. Consequently, electrodes such as gas diffusion electrodes (GDEs) become essential for operating at commercially relevant current densities. However, the application of GDE-based catalysts poses challenges due to their inherent low stability3. In addressing these issues, a pulsed electrolysis method to enhance the performance of electrochemical CO2RR on tin for formate production in GDE-based cells is proposed. While GDE-based electrodes can overcome mass transfer limitations, the overall energy efficiency of an electrochemical system is crucial for economically viable processes. Thermodynamic analysis reveals that above 90 % of the overall energy in CO2RR is consumed in driving the oxygen evolution reaction at the anode4. To improve economic feasibility, it is imperative to either reduce the cell voltage or generate a more economically viable product at the anodic reaction. In this regard, it is proposed replacing the anodic oxygen evolution reaction with a chlorine evolution reaction to enhance energy efficiency. Given the significantly higher market demand for chlorine compared to oxygen, this modification has the potential to reduce overall expenses and enhance the economic viability of the process.

Keywords: CO2 reduction, Formate, Gas diffusion electrode, Pulse electrolysis

References:
1. Rojas, M. I., Esplandiu, M. J., Avalle, L. B., Leiva, E. P. M. & Macagno, V. A. The oxygen and chlorine evolution reactions at titanium oxide electrodes modified with platinum. Electrochim. Acta 43, 1785–1794 (1998).
2. Agarwal, A. S., Zhai, Y., Hill, D. & Sridhar, N. The electrochemical reduction of carbon dioxide to formate/formic acid: Engineering and economic feasibility. ChemSusChem 4, 1301–1310 (2011).
3. Wu, J., Risalvato, F. G., Ma, S. & Zhou, X. D. Electrochemical reduction of carbon dioxide III. the role of oxide layer thickness on the performance of Sn electrode in a full electrochemical cell. J. Mater. Chem. A 2, 1647–1651 (2014).
4. Verma, S., Lu, S. & Kenis, P. J. A. Co-electrolysis of CO2 and glycerol as a pathway to carbon chemicals with improved technoeconomics due to low electricity consumption. Nat. Energy 4, 466–474 (2019).