title: Carbon segregation-induced highly metallic ni nanoparticles for electrocatalytic oxidation of hydrazine in alkaline media.
abstract: The important roles of Ni in electrocatalytic reactions such as hydrazine oxidation are limited largely by high oxidation states because of its intrinsically high oxophilicity. Here, we report the synthesis and properties of highly metallic Ni nanoparticles (NPs) on carbon black supports. We discovered that the heat treatment of as-prepared Ni NPs with an average particle size of 5.8 nm produced highly metallic Ni NPs covered with thin carbon shells, with negligible particle coarsening. The carbon shells were formed by the segregation of carbons in the Ni lattice to the surface of the Ni NPs, leaving highly metallic Ni NPs. X-ray photoelectron spectroscopic analyses revealed that the atomic ratio of metallic Ni increased from 19.2 to 71.7% as a result of the heat treatment. The NPs exhibited higher electrocatalytic activities toward the hydrazine oxidation reaction in alkaline solution, as compared to those of the as-prepared Ni NPs and commercial Ni powders.
authors.affiliation: Clean Energy Research Center and ⊥Fuel Cell Nanomaterials Center, University of Yamanashi , 4 Takeda, Kofu 400-8510, Japan.
authors.forename: Tae-Yeol
authors.initials: TY
authors.lastname: Jeon
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Miyatake
keywords: carbon segregation; electrocatalyst; hydrazine oxidation; nickel nanoparticle