| abstract |
A metal catalyst containing fine metal particles, characterized in that the fine metal particles have a particle diameter of 3 nm or less and have a proportion of a metal in the state of a metallic bonding of 40 % or more, which proportion is determined through subjecting a peak ascribed to the bonding energy inherent in a metal being measured by an X-ray photon analyzer, to a wave form separation. Platinum fine particles are preferred as the above fine metal particles. Preferably, the metal particles are carried on the surface of carrier particles by a method comprising reducing a metal ion generating the metal particles by the action of a reducing agent to thereby precipitate the metal in the form of fine particles on the surface of carrier particles. Further, the above fine metal particles can have the above-mentioned proportion of a metal in the state of a metallic bonding, through the decrease of its oxidation state by the reduction after precipitation. |