Electrochemical reduction of CO2 to formic acid: a study of operating parameters in a microfluidic cell

To meet the enhancement of the energy demand, the increased use of fossil fuels has resulted in a significant release of CO2 into the atmosphere [1]. Continuous carbon dioxide emissions cause considerable environmental damage, so industries and research centres want to find a way to deal with them [2]. Nowadays, the electrochemical conversion of CO2 is considered a relevant topic for several reasons, including the possibility to synthesize chemicals and/or fuels. The aim of the research is to find the operative conditions which allow to maintain at the same time high current density, high Faradic Efficiency, low energy consumption, long-term stability, and increase the final concentration of liquid products. These conditions were tested in a microfluidic cell. The application of continuous-flow micro-fluidic devices for the synthesis of chemicals received increasing attention in chemical engineering in the last years [3]. Especially, in this study, we have investigated the cathodic reduction of CO2 (CO2CR) to formic acid at tin cathodes in undivided microfluidic electrochemical cells characterized by very small inter-electrode distances: 250, 120 and 75 μm with and without supporting electrolyte [2]. The effects of numerous operating parameters such as pH, flow rate and current density were investigated.