▎ 摘　　要

NOVELTY - A catalyst composition comprises a metal catalyst, a carbon material comprising a nitrogen-containing group, which supports the metal catalyst, and an ionomer. USE - Composition is used for forming catalyst layer for forming membrane electrode assembly of polymer electrolyte fuel cell (all claimed). ADVANTAGE - The catalyst layer formed using the composition has improved catalytic activity and durability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a membrane electrode assembly, which comprises a solid electrolyte membrane (107), a gas diffusion layer (101), and a catalyst layer (103,105) comprising the composition; and (2) the carbon material comprising nitrogen-containing group. DESCRIPTION OF DRAWING(S) - The drawing shows a typical sectional view of a structure of the polymer electrolyte fuel cell. Polymer electrolyte fuel cell (100) Gas diffusion layer (101) Catalyst layers (103,105) Solid electrolyte membrane (107) Separator (109)