Selective synthesis and characterization of metallic cobalt, cobalt/platinum, and platinum microspheres

Metallic cobalt microspheres have been successfully synthesized via a facile hydrothermal method in the presence of poly (N-vinyl-2-pyrrolidone) (PVP), and the diameters of these spheres are in the range of 1–2 μm. Bimetallic Co/Pt microspheres and hollow noble metal Pt microspheres have also been selectively synthesized by adjusting the amount of reactants of replacement reaction in which corresponding noble metal compound and metallic cobalt microspheres are used as starting materials. The study on catalytic activities of the as-prepared metallic microspheres on hydrolysis of ammonia-borane for hydrogen generation reveals that Co/Pt (molar ratio 5:1) bimetallic microspheres are far more active than the hollow noble metal Pt microspheres.

Research highlightsMetallic cobalt microspheres have been successfully synthesized via a facile hydrothermal method in the presence of poly (N-vinyl-2-pyrrolidone) (PVP), and the diameters of these spheres are in the range of 1–2 μm. Bimetallic Co/Pt microspheres and hollow noble metal Pt microspheres have also been obtained via a replacement reaction route using metallic Co microspheres as sacrificial templates. The catalytic activities of the as-prepared metallic microspheres for hydrogen generation by hydrolysis of ammonia borane have been investigated; the results show much enhanced favorable catalytic performance of Co/Pt (molar ratio 5:1) bimetallic microspheres with the larger BET surface area comparing with the hollow Pt spheres, providing a new possible alternative in the making of portable fuel cells.