Porous Calcium-Silicate-Hydrate as a Low-Cost Nano-Platform for Ultra-High CO₂ Capture and Storage

CO₂ capture and storage have been regarded as promising concepts to reduce anthropogenic CO₂ emissions. However, the high cost, inferior adsorption capacity, and higher effective activation temperature of traditional sorbents limit their practical application in efficient CO₂ capture. Here, a C-S-H@ZIF-8 (C-S-Z) sorbent is fabricated by in situ growth of the ZIF-8 shell on the C-S-H (calcium-silicate-hydrate) surface for ultra-high CO₂ adsorption and storage. Among the C-S-Z, the outer ZIF-8 shell acts as a transport channel that promotes CO₂ absorption toward the underlying C-S-H substrate for accelerated carbonation while preventing nitrogen and water from reaching the interior C-S-H. As a consequence, C-S-Z possesses the merits of ample pyrrolic nitrogen, porous structure, and ultra-high surface area (577.18 m² g^-1), that contribute to an ultra-high CO₂ capture capacity, reaching 293.6 mg g^-1. DFT calculations show a high CO₂ adsorption energy and the mineral carbonation is dominant by the adsorption process. In particular, the advantages of the outstanding adsorption capacity, low cost, and high CO₂ selectivity make this C-S-H-based sorbent hold great potential in the practical application for direct air CO₂ capture and storage.