Graduate Student Muhammad Bilal

"Electrochemical Carbon Capture and Concentration by Advanced Electrodes Design"

The need to achieve net-zero emissions of anthropogenic CO2 by the end of the twenty-first century has recently raised interest among researchers to develop electrochemical CO2 capture technologies due to their high selectivity, low energy consumption, and ease to be powered with renewable electricity.[1] Currently, most carbon capture technologies rely on the use of expensive sorbents, electrode materials, and ion-selective membranes, and are difficult to scale. Supercapacitive swing adsorption (SSA) is a technique that only requires activated carbon electrodes, a separator, and an aqueous electrolyte to capture and concentrate CO2 during the capacitive charging and discharging of carbon electrodes, making it attractive from the cost and environmental perspectives. Recent studies on SSA focused on improving the energetic and adsorptive performance by tuning the electrolyte concentration, composition, and electrode charging protocols. However, the adsorption capacity of CO2 stayed around 100 mmol/kg (compared to ∼1000 mmol/kg for amine scrubbing), even with higher electrolyte concentrations and extended voltage windows. To overcome this challenge, we developed advanced activated carbon-based electrodes from biomass, coke, coal, and carbide sources and achieved record-high capacitance (250 F/g compared to 80 F/g) and CO2 adsorption capacity (270 mmol/kg compared to 60 mmol/kg).[2] The effect of pore size, surface area, and surface functional groups on SSA performance was investigated. We further showed that increasing the electrochemical potential window up to 1.4V led to 35% increase in the adsorption rate and 48% increase in the adsorption capacity of the electrodes.[3] The charging and discharging of the electrodes over multiple cycles showed highly reproducible CO2 capture and concentration profiles, without any significant performance loss. Scaling supercapacitive swing adsorption of CO2 using 12 electrode pairs led to 17% improvement in energy efficiency and stable adsorption capacity values.[4] In conclusion, we emphasize that the integration of enhanced adsorption capacity, reduced energy consumption, and cost-effective electrode material design is crucial to achieving the Department of Energy (DOE) cost targets and realizing a sustainable approach to CO2 capture.
References
[1] M. Rahimi, A. Khurram, T. A. Hatton, Chem. Soc. Rev. 2022.
[2] M. Bilal, J. Li, K. Landskron, Adv. Sustain. Syst. 2023, 2300250, 1.
[3] M. Bilal, J. Li, H. Guo, K. Landskron, Small 2023, 2207834, 2207834.
[4] J. Li, M. Bilal, K. Landskron, ChemRxiv 2023.