Electrochemical CO2 reduction: The role of catholyte-anolyte interactions in formate/formic acid production

Reducing and mitigating CO 2 emissions is crucial to enhancing air quality and preserving the environment. The electrochemical reduction of carbon dioxide is a technology that can convert CO 2 into valuable added products and can offer long-term solutions for addressing the challenges associated with CO 2 emissions. In this work, the role of the anolyte and its interaction with catholyte for electrochemical reduction of CO 2 into formic acid was investigated. Different types of anolyte solutions of different groups including KOH, NaOH, H 2 SO 4, and NaHCO 3 were investigated. In addition, the best anolyte was selected to run an optimization study using response surface methodology as well as to assess the synergy between the anolyte and catholyte concentrations in order to understand their influence on the reduction process. The results suggest that NaOH outperforms other anolytes over the concentration ranges studied. The interaction between anolyte and catholyte concentrations plays a critical role in determining the optimum formic acid concentration, Faradic Efficiency (FE%), energy consumption, and Energy Efficiency (EE%). At the optimum anolyte concentration of 0.92 M and catholyte concentration of 0.11 M, the maximum formic acid concentration, FE%, energy consumption, and EE% of about 821 mg/L, 77%, 2.4 kWh/kg formic acid , and 75%, respectively, were achieved. Overall, this study highlights the significance of the type and concentration of anolyte in determining the overall performance of the CO 2 ECR to formic acid. The possible mechanism for CO 2 ECR to formic acid/formate using NaOH as an anolyte and NaHCO 3 as a catholyte.