TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: The step of heating the catalyst ink to at least partially remove the solvent from the diffusion layer comprises heating the catalyst ink by an amount to remove a substantial entirely of the solvent. In the method: after heating, at least a portion of the co-solvent remains in at least a portion of the electrode; and at least a portion of the co-solvent remains in the electrode until substantially all of the solvent is removed from the electrode or until completion of the heating. The method further comprises joining the electrode to a proton exchange membrane. The heating comprises leaving at least a portion of the co-solvent that is applied to the diffusion layer in an un-evaporated state even after the heating. Preferred Components: The electrolyte comprises a polymer electrolyte. The cathode and the cathode diffusion media are co-formed, and comprise separate layers that are joined together to define a cathode assembly. The fuel cell further comprises: many fuel cells arranged as a fuel cell assembly; a system powered at least in part by the fuel cell assembly, where the system comprises: an anode flow path configured to couple the fuel cells to a fuel source; a cathode flow path configured to couple the fuel cells to an oxygen source; and an electrical circuit coupled to the assembly to accept the electric current from it; and a load coupled to the electrical circuit. The load comprises a mobile platform, which comprises a vehicle drivetrain. The mobile platform comprises an automobile with the assembly comprising a source of motive power.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The co-solvent has a boiling point that is above at least 100 degrees C, preferably at least 139 degrees C. The co-solvent comprises: alcohol; a mixture; and up to 65 or 10 wt.% of the catalytic ink solution. The co-solvent is propylene glycol butyl ether, ethylene glycol, 1-pentanol, 2,3-butanediol or diacetone alcohol. The solvent comprises at least one of water and an alcohol.