Patent ID: 7479469

Claim:
Electrode catalyst fine particles comprising fine metal particles consisting essentially of one or more metals selected from the group consisting of Au, Ag, Pd, Pt, Rh, Cu, Fe, Ni, Co, Sn, Ti, In, Al, Ta, Sb, Rn, Mo and Cr and having an average particle diameter of 2 to 200 nm supported on carrier particles having an average particle diameter of 10 nm to 10 μm, wherein a potential difference (absolute value of (II) minus (I)) between a flow potential (I) of a water dispersion of the fine metal particles at 1 wt % concentration and a pH of 3 to 8 and a flow potential (II) of a water dispersion of the carrier particles at 1 wt % concentration and a pH of 4 to 10, is in the range of 10 to 3000 mV, and wherein the electrode catalyst fine particle is obtained by mixing a dispersion of the fine metal particles and a dispersion of the carrier particles, and then adjusting the pH of the dispersion mixture in the range of 2 to 10.