Catalyst carrying fine metal particles and use thereof

A method for producing a fine metal particle-carrying catalyst comprising a carrier formed of a conductive material and core-shell structured fine metal particles supported on the carrier, wherein the shell portion is formed of a precious metal and the core portion is formed of a metal less precious than that of the shell portion, the method comprising:

• producing fine particles formed of a non-precious metal by subjecting a compound containing the core-forming non-precious metal element to reduction in a fluid reaction mixture in the presence of the carrier, but in absence of the precious metal while maintaining the temperature of the fluid reaction mixture in a range of 20° C. to 60° C.;
• forming a shell of the precious metal on the respective surfaces of the fine non-precious metal particles as the cores by adding a compound containing the shell-forming precious metal element to the fluid reaction mixture in which the carrier and the fine particles of the non-precious metal produced via the reduction are present and further reducing this compound while maintaining the temperature of the fluid reaction mixture in a range of 20° C. to 60° C., wherein the temperature of the reaction mixture is maintained in the range of 20° C. to 60° C. until after the shell of the precious metal is formed on the surfaces of the non-porous metal particles;
• and
• collecting, from the fluid reaction mixture, a catalyst in which fine metal particles are supported on the carrier, with each metal particle having the shell portion formed of the precious metal and the core portion formed of the non-precious metal.