Sumitomo Electric Industries, Limited

Kouji Yamaguchi

Masatoshi Majima

Kohei Shimoda

The present invention relates to a metal catalyst containing fine metal particles, characterized in that the fine metal particles have a particle diameter of 3 nm or less and also have a proportion of metallic bond state of 40% or more, which is ascribed by subjecting to waveform separation of a binding energy peak peculiar to the metal as measured by using an X-ray photoelectron spectrometer. The fine metal particles are preferably fine platinum particles. The fine metal particles are preferably supported on the surface of carrier particles by reducing ions of metal to be deposited through the action of a reducing agent in a reaction system of a liquid phase containing the carrier particles dispersed therein, thereby to deposit the metal on the surface of carrier particles in the form of fine particles. The proportion of metallic bond state of the fine metal particles is adjusted within the above range by reducing after deposition thereby to decrease the oxidation state.

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Osaka, Japan

Kouji Yamaguchi