▎ 摘　　要

NOVELTY - Manufacture of sulfo-group-containing graphene oxide involves reacting a sulfonating agent including a sulfophenyl group, introducing a sulfophenyl group to the carbon atom of graphene oxide, again introducing sulfophenyl group to the obtained sulfo group-containing graphene oxide, and removing the sulfonating agent. USE - Manufacture of sulfo-group-containing graphene oxide used for forming film of solid polymer electrolyte membrane for membrane electrode assembly for polymer electrolyte fuel cell (all claimed) for electric power generation for fuel-cell vehicle. ADVANTAGE - The method enables effective manufacture of sulfo-group-containing graphene oxide provides the membrane electrode assembly having suppressed cross-leakage of fuel while ensuring excellent proton conductivity and insulation properties. The polymer electrolyte fuel cell has excellent fuel efficiency and power generation performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) manufacture of solid polymer electrolyte membrane (15), which involves mixing the sulfo group-containing graphene oxide and the electrolyte polymer in liquid medium to obtain mixed dispersion and forming into film; (2) manufacture of membrane electrode assembly (10), which involves providing anode (13) having a catalyst layer (11), a cathode (14) having a catalyst layer, and the solid polymer electrolyte membrane which is arranged between the anode and the cathode; and (3) manufacture of polymer electrolyte fuel cell, which involves providing membrane electrode assembly. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic cross-sectional view of the membrane electrode assembly. Membrane electrode assembly (10) Catalyst layer (11) Anode (13) Cathode (14) Solid polymer electrolyte membrane (15)