Microemulsion-mediated synthesis of cobalt (pure fcc and hexagonal phases) and cobalt-nickel alloy nanoparticles.

摘要: By choosing appropriate microemulsion systems, hexagonal cobalt (Co) and cobalt-nickel (1:1) alloy nanoparticles have been obtained with cetyltrimethylammonium bromide as a cationic surfactant at 500 degrees C. This method thus stabilizes the hcp even sizes (<10 nm) which normally fcc is predicted to be stable. On annealing in H-2 700 C we could transform them nanoparticles. Microscopy studies show formation of spherical cubic forms Co-Ni average size 4, 8 20 nm, respectively. Electrochemical that catalytic property towards oxygen evolution dependent on applied voltage. At low voltage (less than 0.65 V) Co (hexagonal) are superior (Co-Ni) while above this more efficient catalysts. The (hcp fcc) ferromagnetism. saturation magnetization is reduced compared bulk possibly due surface oxidation.