A membrane-electrode assembly in a polymer electrolyte/proton exchange membrane fuel cell includes the electrodes (anode and cathode), with a thin layer of catalyzed conductive support particles bonded to either side of the membrane. Where the polymer membrane comprises pendant chains of fluorinated carbon atoms with mobile proton containing terminal groups, proton conductivity with the catalyst particles is improved by chemically attaching like pendant chains to carbon atoms at surfaces of carbon particles. In certain implementations, an amino aryl perfluorinated sulfonic acid precursor is prepared. This precursor is converted to an aryl diazonium cation in the presence of carbon particles. The diazonium cation is reduced to the aryl radical which reacts with carbon atoms of the carbon substrate.