Manufacturing of Two-Dimensional Metal-Organic Framework Nanosheets by Two-Phase Solution Method

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This grant supports research that contributes new knowledge in the manufacturing of two-dimensional metal-organic framework nanosheets, which are a new class of technologically important materials. Two-dimensional materials have attracted significant attention due to their unique properties in comparison to their bulk counterparts. Two-dimensional metal-organic framework nanosheets have emerged and received interest due to their atomically-thin layers and large surface areas with highly accessible active sites. The judicious combination of varied metal clusters and organic ligands generate desired structural and functional properties, which make two-dimensional metal-organic framework nanosheets occupy a rather unique place in the field of two-dimensional materials. However, all reported synthesis is on a lab scale through sonication-assisted approaches causing low product yield, low purity, and low aspect ratio. This award supports fundamental research to provide needed knowledge for the development of a two-phase solution manufacturing process. The new process enables large scale manufacturing of two-dimensional metal-organic frameworks with high aspect ratios and fewer defects. Two-dimensional metal-organic framework nanosheets have many potential applications, such as separations and catalysis, which benefit the chemical and energy industries and, thus, the nation's economy and prosperity. This research involves several disciplines including chemistry, chemical engineering, materials science, and manufacturing. The multi-disciplinary approach helps broaden participation of women and underrepresented groups and K-12 students in research and positively impact Science, Technology, Engineering and Math education.The study of the two-phase solution method provides a fundamental understanding of diffusion-controlled approach to the bi-phase process design by elucidating the roles of deprotonating agent, capping agent, and modulator. It also provides a general principle to improve scalable nanomanufacturing of two-dimensional metal-organic framework nanosheets by studying the processing kinetics and testing on a series of new material sets. The research team studies factors affecting growth direction and crystal size of the metal-organic framework nanosheets and develops a method to control the interlayer forces in these nanosheets. A series of capping agents, modulators, and deprotonating agents are explored to elucidate their effects, while different metal ions, anions, and ligand structures are used to manufacture these unique two-dimensional nanosheet materials. Results from this research fills the knowledge gap on the mechanisms of nanosheets formation during metal-organic framework synthesis from many different material sets.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.