ELECTRODE CATALYST, COMPOSITION FOR FORMING GAS DIFFUSION ELECTRODE, GAS DIFFUSION ELECTRODE, MEMBRANE-ELECTRODE ASSEMBLY, AND FUEL CELL STACK

摘要

Provided is a catalyst for electrodes that is capable of exhibiting sufficient performance, even if containing a comparatively high concentration of chlorine, is suitable for mass production, and is suitable for reducing production costs. The catalyst for electrodes has a core-shell structure including a carrier, a core section formed upon the carrier, and a shell section formed so as to cover at least part of the surface of the core section. The catalyst for electrodes simultaneously fulfills conditions indicated by formula (1) and formula (2). (X1/M) = 1.2 (1). (X2/M) = 47.0 (2). [In formula (1) and formula (2), M indicates the amount of constituent metal atom material (number of atoms) in the shell section, X1 indicates the amount of bromine (Br) material (number of atoms), and X2 indicates the amount of chlorine (Cl) material (number of atoms).]