Our recent publication in Advanced Materials (Synthesis of 2D porous crystalline materials in simulated microgravity) has been highlighted in the main cover of the current issue of Advanced Materials. The paper authored by Noemí Contreras-Pereda as a first author and in collaboration with Dr. Josep Puigmartí-Luis, demonstrates how to generate simulated microgravity on Earth to grow 2D porous crystalline molecular frameworks such as 2D metal-organic frameworks and 2D covalent organic frameworks.
The team of researchers synthesized a conductive bidimensional metal-organic framework (MOF) –specifically Ni3(HITP)2, an exemplar case for growth controllability of MOFs– within a microfluidic device consisting of two substrates sandwiched with a thin silicon film. The solution, including the reactants, was injected into the device via inlet ports. The vapor-induced crystallization of the material was obtained by controlling the diffusion of ammonia gas and air. Different substrates were used (such as quartz and gold) and the result of the process was, in each case, the formation of a smooth, compact and defect-free continuous film, reaching a few-centimeter size.
While the same reaction performed in standard laboratory conditions leads to precipitation of some components and irregular growth, the use of this microfluidic device allows controlling the steps of the process and obtaining a greatly better outcome. This confirms the authors’ intuition, supported by numerical simulation, that the environment created in this device reproduces what observed in the experiments conducted on the International Space Station as an effect of microgravity conditions.
Other structures were synthesized by functionalizing the surface in various ways or using different reactants to explore the versatility of this approach. It proved efficient in growing homogeneous and large thin films of crystalline materials in a wide variety of substrates, with remarkable control over their orientation and morphology. As such, it represents a useful tool for chemists, physicists and material scientists to produce high-quality samples of 2D functional materials in their laboratories.
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