Controlling in-situ generated bubble dynamics via surfactants for efficient bicarbonate electrolysis

Direct bicarbonate electrolysis is gaining attention as a cost-effective strategy by eliminating the need for CO 2 regeneration. Despite this advantage, the practical application is currently hindered by issue of high operating voltage. Herein, we introduce a surfactant-mediated electrolyte engineering approach designed to mitigate the voltage issue at high current densities in bicarbonate reduction. To address the high voltage arising from coexistence of regenerated CO 2 and the electrolyte within the mass-transfer pathway, we optimized the mass transfer pathway by modulating bubble dynamics via a surfactant. In bicarbonate electrolysis, the surfactant significantly lowered the cell voltage at high currents while maintaining the CO 2 conversion efficiency. Bubble dynamics experiments demonstrated that the surfactant effectively suppresses bubble growth and substantially lowers the adhesive force to the electrode surface. The formation of these conductive pathways through bubble interstices effectively minimized the resistance, thereby lowering the cell voltage at high currents. This study establishes a novel approach for high-efficiency bicarbonate reduction, offering a scalable pathway to resolve the critical challenges associated with bubble dynamics.