Facile Synthesis of Co–B Amorphous Alloy in Uniform Spherical Nanoparticles with Enhanced Catalytic Properties

Control of the size and morphology of metallic nanomaterials enables mastery of their properties to enhance their catalytic performances. In this work, uniform Co–B amorphous alloy nanoparticles were synthesized by a simple chemical reduction of [CoX4]− with BH4– in the presence of Bu4P+. With the characterization of X-ray diffraction, selective area electronic diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry, and transmission electron microscopy, the resulting Co–B spherical nanoparticles were identified to be amorphous alloys in an average particle size around 55 nm. The synergistic effect of the halide anion and Bu4P+ cation is essential for the formation of monodisperse and uniform spherical nanoparticles. During the Heck-type carbon–carbon coupling reactions and the hydrogenation of butyraldehyde to n-butanol, the as-synthesized Co–B catalyst was extremely active compared with the conventional Co–B obtained via the direct reduction of cobalt ions with BH4– in aqueous solution. In addition, the as-prepared Co–B amorphous alloy also exhibited recyclability during the hydrogenation of butyraldehyde due to better thermal stability, which was related to the higher surface B content and the uniform particle size.