Search

The fundamental chemical and structural diversity of metal–organic frameworks (MOFs) is vast, but there is a lack of industrial adoption of these extremely versatile compounds. To bridge the gap between basic research and industry, MOF powders must be formulated into more application-relevant shapes and/or composites. Successful incorporation of varying ratios of two different MOFs, CPO-27-Ni and CuBTTri, in a thin polymer film represents an important step toward the development of mixed MOF mixed-matrix membranes. To gain insight into the distribution of the two different MOFs in the polymer, we report their investigation by Cryo-scanning electron microscopy (Cryo-SEM) tomography, which minimizes surface charging and electron beam-induced damage. Because the MOFs are based on two different metal ions, Ni and Cu, the elemental maps of the MOF composite cross sections clearly identify the size and location of each MOF in the reconstructed 3D model. The tomography run was about six times faster than conventional focused ion beam (FIB)-SEM and the first insights to image segmentation combined with machine learning could be achieved. To verify that the MOF composites combined the benefits of rapid moisture-triggered release of nitric oxide (NO) from CPO-27-Ni with the continuous catalytic generation of NO from CuBTTri, we characterized their ability to deliver NO individually and simultaneously. These MOF composites show great promise to achieve optimal dual NO delivery in real-world medical applications.

Hollow nanohexagons with a core–shell structure have been synthesized from a mixture of Ni and Co hydroxide by a mild wet chemical approach. Ni(OH)2@Co(OH)2nanohexagons with controllable sizes of about 200nm, morphology and structure are obtained. Comprehensive microstructure analysis reveals that the Ni(OH)2and Co(OH)2components are single-crystalline. The surfaces of the nanohexagons are smooth and their inner facets can be controlled to be parallel to the outer facets or rotated by 30°. A growth mechanism depending on the N2H4·H2O content and reaction temperature has been proposed to explain the different structures. The parallel inner facets tend to form with higher amounts of N2H4·H2O while the rotated ones tend to form at higher temperature. The specific capacitance of the hollow nanohexagon is about 369F/g, which can be remained as high as 96.4% after 2500 cycles at current density of 1A/g.

In this article, we examine the phenomenon of single-crystal halide salt wire growth at the surface of porous materials. We report the use of a single-step casting technique with a supramolecular self-assembly gel matrix that upon drying leads to the growth of single-crystal halide (e.g., NaCl, KCl, and KI) nanowires with diameters ∼130–200 nm. We demonstrate their formation using electron microscopy and electron-dispersive X-ray spectroscopy, showing that the supramolecular gel stabilizes the growth of these wires by facilitating a diffusion-driven base growth mechanism. Critically, we show that standard non-supramolecular gels are unable to facilitate nanowire growth. We further show that these nanowires can be grown by seeding, forming nanocrystal gardens. This study helps understand the possible prefunctionalization of membranes to stimulate ion-specific filters or salt efflorescence suppressors, while also providing a novel route to nanomaterial growth.

Crystalline Dy2O3, Sc2O3, and amorphous high-kDyScO3thin films have been deposited on Si(100)substrates by metallorganic chemical vapor deposition (MOCVD) using two metal precursors M(EDMDD)3[M=Dy, Sc; EDMDD=6-Ethyl-2,2-Di Methyl -3,5-Decane Dionato]. The precursors were evaluated in terms of efficiency and growth rate under various conditions, viz. vaporizer and susceptor temperatures, reactor pressure, injection rate, and injection delay between the two precursors. Amorphous DyScO3films with nearly correct stoichiometry were deposited within the temperature range of 560–700°C. These amorphous films were smoother than the crystalline binary oxides and reached a density of around 85% of the bulk crystalline density. Amorphous structure and surface smoothness retained up to an annealing temperature as high as 950°C. The thickness of the SiOxinterlayer did not vary with deposition temperature, but annealing at temperatures above 900°C increased the interlayer thickness. Electrical properties are promising; the dielectric constant of DyScO3(k≈22)is much higher than that of the binary oxides Dy2O3and Sc2O3(k≈10), and the leakage currents are very low compared to SiO2.