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The applications of semiconductor nanocrystals in optoelectronics are based on the unique characteristic of quantum confinement. There is great interest to tailor the performance of optoelectronic nanodevices and systems through the control of the sizes of nanocrystals. In this work, we develop a general mathematical formulation for the growth of a crystal/particle in a liquid solution, which takes account of the combinational effect of diffusion-limited growth and reaction-limited growth, and formulate the growth equations for the size of a cubic crystal grown under three different scenarios – isothermal and isochoric conditions, isothermal growth with the evaporation and/or extraction of the solvent and isochoric growth with continuous change in temperature. For the growth of a cubic crystal under isothermal and isochoric conditions, there are three growth stages – linear growth, nonlinear growth and plateau, and the growth rate in the stage of linear growth and the final size of the cubic crystal are dependent on the degree of supersaturation. For the growth of multi-crystals with a Gaussian distribution of crystal sizes, the change of the monomer concentration in a liquid solution is dependent on the change rates of average size and the standard deviation of the crystal sizes.
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Templated interfacial synthesis of metal-organic framework (MOF) nano- and micro-structures with precisely controlled shapes and sizes
Abstract Metal-organic frameworks (MOF) are an emerging class of microporous materials with promising applications. MOF nanocrystals, and their assembled super-structures, can display unique properties and reactivities when compared with their bulk analogues. MOF nanostructures of 0-D, 2-D, and 3-D dimensions can be routinely obtained by controlling reaction conditions and ligand additives, while formation of 1-D MOF nanocrystals (nanowires and nanorods) and super-structures has been relatively rare. We report here a facile templated interfacial synthesis methodology for the preparation of a series of 1-D MOF nano- and micro-structures with precisely controlled shapes and sizes. Specifically, by applying track-etched polycarbonate (PCTE) membranes as the templates and at the oil/water interface, we rapidly and reproducibly synthesize zeolitic imidazolate framework-8 (ZIF-8) and ZIF-67 nano- and micro structures of sizes ranging from 10 nm to 20 μm. We also identify a size confinement effect on MOF crystal growth, which leads to single crystals under the most restricted conditions and inter-grown polycrystals at larger template pore sizes, as well as surface directing effects that influence the crystallographic preferred orientation. Our findings provide a potentially generalizable method for controlling the size, morphology, and crystal orientations of MOF nanomaterials, as well as offering fundamental understanding into MOF crystal growth mechanisms.
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- Award ID(s):
- 2101535
- PAR ID:
- 10234531
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Chemistry
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2399-3669
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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