Effect of surface composition of Pt-Au alloy cathode catalyst on the performance of direct methanol fuel cells

A pure Pt cathode catalyst in direct methanol fuel cells is not only favored for oxygen reduction but also for the unwanted oxidation of methanol that permeates from the anode. Based on the idea that alloying another metal can alter the surface structure of Pt and hence reduce the active sites for methanol adsorption, in this work we prepare carbon supported Pt-Au nanoparticles with different surface compositions with the dimethylformamide co-reduction method by adjusting the pH value from 14 to 12. The electrochemical characterizations indicate that the alloyed Pt-Au catalyst prepared under pH = 13 exhibits lower catalytic activity to methanol oxidation but retains the oxygen-reduction activity similar to that of the Pt/C. The cell performance tests show that the PtAu/C can almost double the peak power density of the cell with the Pt/C cathode, although the Pt loading in the PtAu/C cathode is only half of that in the Pt/C cathode.