Global warming due to anthropogenic CO2 emissions demands the rapid development of efficient carbon capture technologies. Supercapacitive swing adsorption (SSA) is a technology that relies on the reversible charge and discharge of supercapacitor electrodes to selectively adsorb and desorb CO2. A current limitation of SSA is the low sorption capacity. Here, we investigate a series of activated carbons derived from biomass, coke, coal, and carbide as electrode materials for SSA. The energetic and adsorptive performance metrics are quantitatively analyzed and their relationship with double layer capacitance, real capacitance, imaginary capacitance, and diffusion resistance is studied. The results show that there is a strong positive correlation between specific capacitance and CO2 adsorption capacity. The highest gravimetric sorption capacity was measured for garlic-root derived activated carbons valuing 273 mmol.kg-1 for 4 cm2 electrodes having a specific capacitance of 257 F.g-1. This is a ~4-fold increase compared to BPL 4x6 carbon having a specific capacitance of 86 F.g-1 and an adsorption capacity of 70 mmol.Kg-1. Volumetric specific capacitances and volumetric sorption capacities are also correlated. The highest volumetric sorption capacity was found for garlic powder-derived activated carbon valuing 65.3 mol.m3 at a volumetric specific capacitance of 62.3 F.cm3 which is a two-fold increase compared to BPL 4x6 carbon which has a volumetric specific capacitance of 41.2 F/cm3 and a volumetric sorption capacity of 27.1 mol.m3. In addition, higher specific capacitance tends to improve the overall adsorption rate and productivity.

A multicapillary 3D printed solution flow type microdroplet cell (Sf-MDC) is proposed for high-throughput local anodizing. The optimally designed 3D printed Sf-MDC offers low resin consumption, shorter fabrication time and increased throughput. The Sf-MDC consists of three solution inlets separately connected with inner capillaries, a common solution outlet for removing the excess solution from outer capillaries and a two-electrode system with a common Pt counter electrode. Three major acidic electrolytes, i.e. 0.3 M H2SO4, 0.22 M (COOH)2 and 0.1 M H3PO4 are used for simultaneous local anodizing. The simultaneously anodized lines exhibit uniform length, width and porous structure for each anodizing solution. Relationship between anodized line width, diameter of capillaries, inlet flow rate and vacuum pressure is studied. By varying the concentration of (COOH)2 electrolyte inside each inner capillary, three porous alumina membranes with different oxide thicknesses and pore diameters are simultaneously fabricated. The microcell showed good reproducibility and can be applied for fast fabrication of porous alumina filters and electronic components.

Graphical abstract

Global warming due to anthropogenic CO2 emissions demands the rapid development of efficient carbon capture technologies. Supercapacitive swing adsorption (SSA) is a technology that relies on the reversible charge and discharge of supercapacitor electrodes to selectively adsorb and desorb CO2. A current limitation of SSA is the low sorption capacity. Here, we investigate a series of activated carbons derived from biomass, coke, coal, and carbide as electrode materials for SSA. The energetic and adsorptive performance metrics are quantitatively analyzed and their relationship with double layer capacitance, real capacitance, imaginary capacitance, and diffusion resistance is studied. The results show that there is a strong positive correlation between specific capacitance and CO2 adsorption capacity. The highest gravimetric sorption capacity was measured for garlic-root derived activated carbons valuing 273 mmol.kg-1 for 4 cm2 electrodes having a specific capacitance of 257 F.g-1. This is a ~4-fold increase compared to BPL 4x6 carbon having a specific capacitance of 86 F.g-1 and an adsorption capacity of 70 mmol.Kg-1. Volumetric specific capacitances and volumetric sorption capacities are also correlated. The highest volumetric sorption capacity was found for garlic powder-derived activated carbon valuing 65.3 mol.m3 at a volumetric specific capacitance of 62.3 F.cm3 which is a two-fold increase compared to BPL 4x6 carbon which has a volumetric specific capacitance of 41.2 F/cm3 and a volumetric sorption capacity of 27.1 mol.m3. In addition, higher specific capacitance tends to improve the overall adsorption rate and productivity.

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