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Branched Pd and Pd-based trimetallic nanocrystals with long, thin branches and open structures were synthesized in high yields, which provides an avenue to developing high performance catalysts for methanol electrooxidation.

A simple solution-phase route was developed for the large-scale synthesis of self-organized, closely packed ultralong single crystalline Se nanowire superstructures with diverse morphologies and macroscopic dimensions even extending over several millimeters. The hierarchical architectures of self-organized Se nanowires were formed by reducing H2SeO4 with a bisubstituted aniline, such as 3,5-dimethoxyaniline, 2,5-dimethoxyaniline, 2,6-dimethoxyaniline, and 2-methoxy-5-nitroaniline under solvothermal conditions. Scanning electron microscopy studies show 100% morphological yield and morphological uniformity of the self-organized hierarchical architectures. Based on the dependence of the Se nanostructures on the synthetic conditions, especially the molecular structures of reductants and solvent, we proposed a plausible mechanism to account for the formation of the distinctive morphologies of the self-organized nanowire architectures. The field emission characteristics of the Se nanowires synthesized using 2,6-dimethoxyaniline and 2-methoxy-5-nitroaniline as the reductants are studied. These well-aligned Se nanowires show very low turn-on field (Eto) and threshold field (Ethr) as well as high emission current densities under low applied electric fields, which are superior to most of the one-dimensional (1D) nanostructures reported previously, due to their exceptional aspect ratios (>20 000) and sharp tips in combination with the nature of low band gap and high conductivity of Se. Furthermore, the Se nanowire emitters exhibit good emission current stability with small fluctuations (typically, less than 3%) over a period of 1000 min.

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Branched Pd nanocrystals (NCs) with tunable architectures are synthesized in high yields (>95%) by simply adjusting the concentration of H2PdCl4 in the presence of fixed amounts of cetyltrimethylammonium bromide (CTAB), L-ascorbic acid (L-AA), and CuBr2(-) that is produced by reducing CuBr2 with L-AA. The as-synthesized branched Pd NCs have long, straight branches with thin diameters. At the same time, the growth process of the branched Pd NCs is monitored, which provides mechanistic insights for the branching growth of Pd NCs. It is identified that a high concentration of CTAB combined with an appropriate amount of CuBr2(-) species, acting as an in situ cooperatively organized template, is a decisive factor for the anisotropic growth of the branched Pd nanostructures during aqueous-phase reduction of the Pd precursor, using L-AA as a reducing agent. The electrocatalytic activities of the branched Pd NCs were tested. The branched Pd NCs are found to be an excellent electrocatalyst for the methanol oxidation reaction (MOR) largely due to the size and morphological effects of the branched structures.