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

ABSTRACT

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.