Role of Internal Stress in the Early-Stage Nucleation of Amorphous Calcium Carbonate Gels

Q Zhou and T Du and LJ Guo and G Sant and M Bauchy, APPLIED SCIENCES- BASEL, 10, 4359 (2020).

DOI: 10.3390/app10124359

Featured Application This work offers new insights into the atomic-scale mechanism governing the early-stage nucleation of amorphous calcium carbonate gels, which is the key to the acceleration of the development of new methods, enabling low-cost CO(2)utilization by mineralization. Although calcium carbonate (CaCO3) precipitation plays an important role in nature, its mechanism remains only partially understood. Further understanding the atomic driving force behind the CaCO(3)precipitation could be key to facilitate the capture, immobilization, and utilization of CO(2)by mineralization. Here, based on molecular dynamics simulations, we investigate the mechanism of the early-stage nucleation of an amorphous calcium carbonate gel. We show that the gelation reaction manifests itself by the formation of some calcium carbonate clusters that grow over time. Interestingly, we demonstrate that the gelation reaction is driven by the existence of some competing local molecular stresses within the Ca and C precursors, which progressively get released upon gelation. This internal molecular stress is found to originate from the significantly different local coordination environments exhibited by Ca and C atoms. These results highlight the key role played by the local stress acting within the atomic network in governing gelation reactions.

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