Carbon dioxide adsorption in open nanospaces formed by overlap of saponite clay nanosheets.

Nanoscale open spaces formed by partial overlap of two-dimensional nanosheets in clays, abundantly and ubiquitously available, possess reactive molecular sites such as nanosheet edges in their interior. Here, the capture and storage of CO molecules in open spaces within saponite clay are explored by solid-state nuclear magnetic resonance coupled with open space analysis using positronium. CO physisorption occurs on the nanosheet surfaces inside the open spaces under ambient conditions. Thereby, CO molecules are activated by picking off weakly-bound oxygen from octahedral sites at the nanosheet edges and carbonate species are stabilized on the nanosheet surfaces. This instantaneous mineral carbonation and CO physisorption occurs in the absence of an energy-consumption process or chemical solution enhancement. This finding is of potential significance for CO capture and storage and presents an approach of environmentally friendly recycling of low contaminated soil in Fukushima.