Unraveling the CO2/H2O CO-adsorption mechanism: A dynamic study on templated carbons for CO2 capture

This study evaluated zeolite-templated carbon (ZTC) and soft-templated carbon (STC) for direct air capture (DAC) of CO 2 , examining their synthesis, structural features, adsorption performance, and potential for industrial use. ZTC was produced through chemical vapor deposition using 13× zeolite, revealing a microporous structure (0.72–1.41 nm) and a specific surface area of 2815 m 2 /g. Conversely, STC prepared via a dual-template glucose system demonstrated a hierarchical pore structure (0.69 nm ultra-micropores and 3.05 nm mesopores) with a surface area of 838 m 2 /g. Under pure CO 2 conditions, both materials had similar adsorption capacities (2.16 mmol/g and 2.09 mmol/g, respectively). However, at 400 ppm CO 2 , STC outperformed ZTC (0.013 mmol/g vs. 0.0107 mmol/g) due to its radially oriented pores and hollow cavities, which created an “adsorption-enrichment” pathway, thereby improving low-concentration CO 2 uptake. Under humid conditions (RH = 75%), both materials exhibited two-stage adsorption kinetics, starting with rapid physical adsorption of CO 2 , followed by a water-driven carbonation reaction. Water blocking the hierarchical pores and cavities reduced the adsorption efficiency of STC due to its hydrophilic surface. In contrast, ZTC maintained strong physical adsorption and carbonation reactions in humid environments. Additionally, ZTC's lower cost ($29.60/kg vs. $44.36/kg for STC), scalability, and humidity tolerance make it more suitable for industrial CO 2 capture.