posted on 2022-07-13, 11:33authored bySiavash Zare, Andreas Funk, Mohammad Javad Abdolhosseini
Qomi
Rapid CO2 mineralization in natural and synthetic
metal
silicates provides a potentially scalable solution to address the
untethered global carbon emissions. When metal silicates react with
humidified CO2-rich fluids, a nanometer-thick water film
adsorbs on mineral surfaces. Experiments show that such nanoscale
reactive environments demonstrate an enhanced level of carbonic acid
formation, metal-(bi)carbonate surface complexation, and fast carbon
mineralization. Hindered by the spatiotemporal complexities of in situ measurements at the solid–liquid interface,
the mechanistic picture of carbon mineralization mechanisms in water
films remain obscure. Here, we leverage reactive and nonreactive molecular
simulations to probe the elementary reaction steps involved in the
interaction of bicarbonate with metal silicate surfaces. We observe
that a reverse proton transport between the bicarbonate and surface
hydroxides drives carbonate production and surface metal carbonate
complexation in agreement with in situ spectroscopy
measurements. The resultant carbonate can also contribute to the ligand-enhanced
dissolution that appears to be slightly favorable over carbonate-unassisted
dissolution. We also discuss the potential implications of metal carbonate
complex formation and dissolution on lowering the growth’s
configurational entropy penalty and the rise of interfacial carbon
mineralization pathways.