Optimizing Reactor Configuration and Electrode Geometry for Enhanced Electrochemical Reduction of CO2

The increasing concentration of CO₂ in the atmosphere has contributed significantlyto global warming and its associated environmental effects. Electrochemical conversion hasemerged as a promising approach for CO₂ capture, storage, and utilization to produce valueaddedchemicals. However, the inherently low solubility of CO₂ in aqueous solutions presents amajor challenge to the efficiency of process. Unlike previous studies that focused on increasing CO₂ solubility by lowering the temperature or using non-aqueous solvents, this work exploresthe use of smaller gas bubbles to enhance CO₂ retention time in solution. The objective is toprolong the residence time of CO₂ bubble in the electrolyte, allowing for gradual dissolution,sustained saturation, and improved interaction with the cathode surface. Under the same operatingvoltage, the bubble stone sparger, produces bubbles with diameters of 6.18 and 3.26-timesthan those generated by the atomizer and air stone, respectively, achieved 29.23% and 15.23%higher current efficiency. Similarly, the formic acid yield increased by 50.70% and 28.21%,compared to the other sparger types. The highest current efficiency (11.60%) and formic acidyield (0.122%) were obtained using the bubble stone sparger with a cathode length of 2.5 cm,a cathode-sparger distance of 0.5 cm, and an operating voltage of 6 V. These findings highlightthe potential of using smaller bubble sizes to improve the electrochemical reduction of CO₂ byenhancing gas-liquid interaction and mass transfer performance.

CO2ER; Bubble size effect; Enhance performance

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