Effects of ionomer content on Pt catalyst/ordered mesoporous carbon support in polymer electrolyte membrane fuel cells

► Pt/OMC with high loading was synthesized for polymer electrolyte membrane fuel cells (PEMFCs). ► Electrodes with different ionomer loadings (in the range of 5-30 wt. %) with Pt/OMCs were applied in cathode. ► Pt particles placed on or between two or more carbon nanorods can share and utilize electrolytes. ► Excessive ionomer can trap H2O generated by electrochemical reactions and cause mass transfer problems. ► 10 wt. % Ionomer with prepared Pt/OMCs is determined to be the optimum amount.