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

推进从气体排放和空气中捕获、转化、储存和去除二氧化碳（CO2）的十亿吨级解决方案，对于限制气候变化对环境的不利影响至关重要。碳矿化是利用地球上丰富的纳米多孔硅酸盐将人为CO2转化为碳酸钙或碳酸镁的一种可扩展和有利的方法。碳酸盐产品是稳定的、不溶于水的无机化合物，是二氧化碳储存应用的理想选择。然而，我们对影响碳矿化过程的孔隙尺度界面机制的有限理解挑战了我们预测控制碳酸盐形成的能力。为了应对这一科学挑战，本研究项目将开发具有有序孔隙度的硅质纳米通道，以研究限制条件下的碳酸盐结晶机制。从这些研究中获得的基础知识将为新技术的设计提供信息，这些新技术利用碳酸盐结晶机制进行气体的反应分离，回收高价值金属，并预测注入地质储层的CO2的命运。该研究计划与教育和推广活动紧密结合，重点是培训未来的STEM劳动力，并通过让STEM中代表性不足的群体成员和服务不足的农村社区成员参与，共同创建社区级的碳去除解决方案。该项目将研究尺寸范围为2至20 nm的硅质纳米通道内受限流体中碳酸钙和碳酸镁结晶的结晶机制。将在反应性较低的二氧化硅界面和反应性较强的硅酸钙和硅酸镁表面研究封闭流体中的碳酸盐结晶机制。通过溶胶-凝胶法合成有序孔的阳极氧化铝膜，可以实现对硅质孔的形态和组成控制。碳酸盐结晶的非侵入性和动态表征将通过操作X射线散射和先进的光谱测量来实现。实验结果将用于研究碳酸盐形成的经典和非经典机制的有效性，并在需要时提出新的机制。这些研究活动将作为一个教育和推广平台，通过说明性的练习册，与PBS合作的指导视频以及扩展您的视野和科学中心支持的动手实验模块，让代表性不足的K-12学生参与科学教育和交流。本科生将通过NSF Louis Stokes少数民族参与联盟计划招募和指导，使用与碳转化相关的研究活动作为平台。与气候，能源和环境技术的科学和工程背景下的脱碳相关的主题将通过本科生和研究生的混合学习形式变得更容易获得。研究活动的见解将用于与当地农民通过矿物风化共同创造碳去除解决方案。这个紧密结合的研究、推广和教育活动旨在促进对可持续气候、环境和能源解决方案的热情和参与。这个奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.