Investigation of Nanostructured Bimetallic Pt-Pd Alloy on Functionalized Carbon Supports as a New Cathode for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

Carbon supported Pt-Pd alloy electrocatalysts of different Pt Pdx atomic ratios (x = 0.25, 0.5, 1 and 2) were prepared by the impregnation synthesis method using NaBH4 as a reductive agent. To improve the utilization and activity of cathodic catalysts for ORR reaction, the alloy nanoparticles were loaded on the mixture of Vulcan XC-72 and MWCNT (1:3), which were functionalized in the mixture of 96% sulfuric acid and 4-aminobenzenesulfonic acid using sodium nitrite to produce intermediate diazonium salts. For the synthesized Pt Pdx/C electrocatalysts, the highest catalytic activity for the ORR was found for a Pt:Pd atomic ratio of 2:1 in acidic media. A membrane-electrode assembly (MEA) has been prepared by employing of the modified carbon supported catalyst as a cathode for single cell test and characterized by polarization curves and impedance diagrams. The PEMFC test results indicate that the MEA prepared from modified Pt2Pd/C cathode exhibits better performance compared to the MEA prepared from Pt/C (Electrochem), in terms of maximum power density and minimum charge transfer resistance.