▎ 摘　　要

NOVELTY - A carbon-type conjugate comprises a rare-earth-metal ion and a carbon-type solid acid bonded with the rare-earth-metal ion. USE - Carbon-type conjugate is used as electrolyte or carrier for catalyst used in catalyst layer of membrane electrode junction of solid polymer electrolyte fuel cell (all claimed). ADVANTAGE - The carbon-type conjugate has excellent proton conductivity and electron conductivity, and produces catalyst layer having excellent power generation characteristics. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) catalyst layer, which comprises the carbon-based conjugate; (2) membrane electrode junction, which comprises a solid polymer electrolyte membrane (107), a gas-diffusion layer (101), and the catalyst layer; (3) production of the carbon-based conjugate, which involves reacting the carbon-based solid acid with a rare-earth metal compound; and (4) composition, which comprises the carbon-based conjugate and a perfluoroic-acid-based polymer. DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the polymer electrolyte fuel cell. Polymer electrolyte fuel cell (100) Gas-diffusion layer (101) Anode catalyst layer (103) Cathode catalyst layer (105) Solid polymer electrolyte membrane (107)