Methodology development
of robust linkages is fundamentally important
for the synthesis and application of covalent organic frameworks (COFs).
We report herein a new strategy based on multicomponent reactions
(MCRs) to construct ultrastable COFs. With the one-pot formation of
five covalent bonds in each cyclic joint, a series of imidazole-linked
COFs were robustly constructed through the Debus–Radziszewski
MCR from three easily available components. By reaching a higher level
of complexity and precision in covalent assembly, this research explores
a new direction in integrating sophisticated reversible/irreversible
reactions to construct crystalline porous frameworks.
Nanowire arrays present an excellent candidate for high performance lithium-ion battery electrodes. However, agglomeration in long nanowire arrays impedes nanowire-based electrodes from delivering high areal capacity, by degrading the nanoscale wires to micro-sized bundles and reducing the mechanical stability. In this study, we develop a simple way to fabricate three-dimensional (3D) nickel etin (NieSn) nanowire networks by using 3D porous anodic alumina templates synthesized from lowcost impure aluminum foils. By eliminating agglomeration, stable high areal capacity anodes are demonstrated with 3D self-supporting NieSn nanowire network structures. With a nanowire length of 40 mm, the 3D NieSn nanowire networks can deliver an areal capacity as high as 4.3 mAh cm À2 with a cycle life longer than 50 cycles. The 3D NieSn nanowire networks also exhibit an excellent rate capability with 72% of the capacity retained when the test rate increases from C/5 to 6C.
The wet-chemical synthesis of aluminum nanoparticles was investigated systematically by using dimethylethylamine alane and 1-methylpyrrolidine alane as precursors and molecules with one or a pair of carboxylic acid groups as surface passivation agents. Dimethylethylamine alane was more reactive, capable of yielding well-defined and dispersed aluminum nanoparticles. 1-Methylpyrrolidine alane was less reactive and more complex in the catalytic decomposition reaction, for which various experimental parameters and conditions were used and evaluated. The results suggested that the passivation agent played dual roles of trapping aluminum particles to keep them nanoscale during the alane decomposition and protecting the aluminum nanoparticles postproduction from surface oxidation and that an appropriate balance between the rate of alane decomposition (depending more sensitively on the reaction temperature) and the timing in the introduction of the passivation agent into the reaction mixture was critical to the desired product mixes and/or morphologies. Some fundamental and technical issues on the alane decomposition and the protection of the resulting aluminum nanoparticles are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.