One-dimensional alloy nanowires exhibit substantial application potential in electrocatalysis owing to their high axial surface-to-volume ratio, exposed crystallographic facets, and excellent electrical conductivity that facilitates facile electrode integration. In this study, initial attempts to synthesize nanowires using oleylamine and cetyltrimethylammonium bromide (CTAB) invariably yielded substantial quantities of alloy nanoparticle byproducts, regardless of variations in CTAB concentration or other synthetic parameters. To address this challenge, we systematically investigated the effects of surfactant concentration, surfactant type, and ammonium salts on the competitive formation of CuNi nanowires versus byproduct nanoparticles in oleylamine-mediated reduction systems. This enabled the development of an inverse micelle method that significantly enhances nanowire yield. This approach employs surfactant-stabilized nonpolar oleylamine micelles as microreactors, wherein nanowire nuclei form exclusively within the micellar interior, while the inert polar external phase effectively suppresses extramicellar particle formation. As nucleation proceeds, precursor depletion inside the micelles establishes a concentration gradient that drives continuous influx of precursors from the polar external phase, sustaining the reaction. The size-confining nature of the micelles further directs anisotropic growth, ultimately yielding high-aspect-ratio alloy nanowires. The electrocatalytic performance of the as-synthesized nanowires toward methanol electrooxidation was subsequently evaluated in alkaline media. The nanowires exhibit a pronounced anodic peak at 1.7 V in 1.0 M methanol, achieving a peak current of 4.2 mA, which corresponds to a specific activity of 16.97 mA·cm −2 and a mass activity of 36.52 mA·mg −1 , thereby confirming their high efficiency for the methanol oxidation reaction (MOR). This study establishes rational design principles for micelle-directed nanowire growth and provides a scalable synthetic platform toward robust, platinum-free alloy nanocatalysts.
Wu et al. (Thu,) studied this question.