CAREER: Confinement Induced Structural Evolution of Calcium- and Magnesium- Carbonates in Architected Siliceous Nanochannels

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Advancing gigaton-scale solutions to capture, convert, store, and remove carbon dioxide (CO2) from gas emissions and air is crucial to limit the detrimental environmental impacts of climate change. Carbon mineralization is a scalable and thermodynamically favorable approach for converting anthropogenic CO2 into calcium or magnesium carbonates using earth-abundant nanoporous silicates. The carbonate products are stable, water-insoluble inorganic compounds, ideal for CO2 storage applications. However, our limited understanding of the pore-scale interfacial mechanisms that influence the carbon mineralization process challenges our ability to predictively control carbonate formation. To address this scientific challenge, this research project will develop architected siliceous nanochannels with ordered porosity to investigate carbonate crystallization mechanisms in confinement. The fundamental knowledge gained from these studies will inform the design of new technologies that harness carbonate crystallization mechanisms for the reactive separation of gases, recovery of high-value metals, and predicting the fate of CO2 injected into geological reservoirs. The research program is closely integrated with educational and outreach activities focused on training the future STEM workforce and co-creating community-level carbon removal solutions by engaging members of underrepresented groups in STEM and members of underserved rural communities. This project will investigate the crystallization mechanisms of calcium and magnesium carbonate crystallization in confined fluids within architected siliceous nanochannels with sizes ranging from 2 to 20 nm. Carbonate crystallization mechanisms in confined fluids will be investigated in less reactive silica interfaces and more reactive calcium and magnesium silicate surfaces. Morphological and compositional controls on siliceous pores will be achieved via sol-gel synthesis in anodic alumina membranes with ordered pores. Non-invasive and dynamic characterization of carbonate crystallization will be realized through operando X-ray scattering and advanced spectroscopy measurements. The experimental results will be used to investigate the validity of classical and non-classical mechanisms of carbonate formation and propose new mechanisms if needed. These research activities will serve as an educational and outreach platform for engaging underrepresented K-12 students in science education and communication through illustrative workbooks, mentoring videos in collaboration with PBS, and hands-on experimental modules supported by Expanding Your Horizons and Sciencenter. Undergraduate students will be recruited and mentored through the NSF Louis Stokes Alliances for Minority Participation program using research activities related to carbon transformations as a platform. Topics related to decarbonization in the context of science and engineering for climate, energy, and environmental technologies will be made more accessible through blended learning formats for undergraduate and graduate students. Insights from research activities will be used to co-create carbon removal solutions through mineral weathering with local farmers. The closely integrated research, outreach, and educational activities are designed to foster enthusiasm for and engagement in sustainable climate, environment, and energy solutions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.