3D Modeling and Numerical Investigation of Electrochemical CO2 Reduction in Microfluidic Flow Cells

Electrochemical CO2$\left(\text{CO}\right)_{2}$ reduction reaction is considered as a promising technical route for carbon-neutral and mitigating greenhouse effect. CO2$\left(\text{CO}\right)_{2}$ concentration limitation hinders the performance of state-of-the-art electrochemical CO2$\left(\text{CO}\right)_{2}$ reduction reaction. Increasing the mass transfer of reactants on the catalyst surface by flow cell design and porous electrode design has become the mainstream approach. Studying the distribution of mass in reaction region is important and beneficial to optimizing and designing efficient reactors. Herein, electrochemical CO2$\left(\text{CO}\right)_{2}$ reduction reaction reactors with micrometer and millimeter channels are simulated and systemically analyzed. The results reveal the microfluidic design can improve the mass transfer and reactant gas flow in the porous layer to reduce the concentration polarization and ensure uniform local potential of the reactor. A micrometer channel model requires only 10 sccm inlet gas supply to achieve the same current density compared to a millimeter flow channel with an inlet flow of 20 sccm. This study proposes a reasonable flow channel reactor to reduce gas stagnant region, which not only enhances the CO2$\left(\text{CO}\right)_{2}$ reduction performance effectively with evident potential dependence, but also guides the design for large-scale reactors.