Hierarchically 2D Porous Nanosheets Derived from Clay Minerals for Enhanced Carbon Dioxide Capture.

Carbon dioxide (CO2) capture and storage technologies are key methods for mitigating the greenhouse effect. The development of high-performance adsorbents using abundant natural minerals represents a promising approach to achieving cost-effective CO2 capture. In this work, we report a simple and scalable strategy for preparing two-dimensional (2D) porous nanosheets from the natural layered clay mineral vermiculite as the raw material, via liquid-phase exfoliation and acid etching. The clay-based 2D porous nanosheets exhibited a high specific surface area, a hierarchical porous structure, and mechanical and chemical stability. In the presence of the 2D porous nanosheets, the CO2 capture and adsorption capacity were significantly enhanced. The gas adsorption properties of the porous nanosheets were investigated over a wide temperature range (25-75 °C), achieving a gas uptake capacity of 38.22 mmol/g (at 75 °C and 35 bar). Furthermore, an intrinsic relationship between the pore structure of the porous nanosheets and their gas adsorption performance was revealed. The maximum uptake capacity remained at approximately 36.40 mmol/g during five adsorption-desorption cycles conducted at 75 °C. This work provides a promising approach for further development of clay-derived adsorbents for CO2 capture and may also offer useful implications for understanding CO2 geological sequestration.