A nano-silicate material with exceptional capacity for CO₂ capture and storage at room temperature

In order to mitigate climate change driven by the observed high levels of carbon dioxide (CO₂) in the atmosphere, many micro and nano-porous materials are being investigated for CO₂ selectivity, capture and storage (CCS) purposes, including zeolites, metal organic frameworks (MOFs), functionalized polymers, activated carbons and nano-silicate clay minerals. Key properties include availability, non-toxicity, low cost, stability, energy of adsorption/desorption, sorbent regeneration, sorption kinetics and CO₂ storage capacity. Here, we address the crucial point of the volumetric capture and storage capacity for CO₂ in a low cost material which is natural, non-toxic, and stable. We show that the nano-silicate Nickel Fluorohectorite is able to capture 0.79 metric tons of CO₂ per m³ of host material - one of the highest capacities ever achieved - and we compare volumetric and gravimetric capacity of the best CO₂ sorbent materials reported to date. Our results suggest that the high capture capacity of this fluorohectorite clay is strongly coupled to the type and valence of the interlayer cation (here Ni²⁺) and the high charge density, which is almost twice that of montmorillonite, resulting in the highest reported CO₂ uptake among clay minerals.