Membrane-separated electrodes enable high-rate low-energy electrochemical carbon capture

Source: PubMed Central Open Access, NCBI / U.S. National Library of Medicine

Electrochemical carbon dioxide (CO) capture using supercapacitive systems is a promising green technology but remains limited by low uptake rates and high energy requirement. Here, we present a membrane-integrated supercapacitor system that addresses these challenges by decoupling electrode environments with a cation exchange membrane. This configuration sustains high hydroxide concentration at the gas-facing negative electrode, generated through dynamic water dissociation within the electric double layer. The resulting localized alkaline interface enhances COcapture by driving its conversion into (bi)carbonate species via a pH-swing mechanism. The system achieves a COuptake of up to 893 mmol/kg with a fast rate of 1281 mmol/kg/hour at −1.4 V under 20% CO. Energy consumption as low as 32 kJ/mol is obtained at −0.8 V under 20% COtogether with a long lifetime over 200 hours at −1.0 V, 10% CO. These findings establish a robust platform for electrochemical COcapture and underscore the importance of localized chemical environments in supercapacitive swing adsorption. Controlling local chemistry with membranes enables fast, low-energy electrochemical carbon dioxide capture. teaser