INK, FUEL CELL CATALYST LAYER FORMED BY USING THE INK AND USES THEREOF

There is provided an ink for forming a fuel cell catalyst layer that is capable of efficiently forming a high-performance fuel cell catalyst layer inexpensively. The ink for forming a fuel cell catalyst layer of the present invention comprises a fuel cell catalyst, an electron conductive material, a proton conductive material and a solvent, wherein the fuel cell catalyst comprises a metal-containing oxycarbonitride that contains niobium and/or titanium; the mass ratio [(A)/(B)] of the content (A) of the fuel cell catalyst to the content (B) of the electron conductive material is 1 to 6; and the mass ratio [(D)/(C)] of the content (D) of the proton conductive material to the total content (C) of the fuel cell catalyst and the electron conductive material is 0.2 to 0.6.