Metal Oxide Modified Pt-based Anode Catalysts For Direct Methanol Fuel Cells

Pt-based anode catalysts of direct methanol fuel cells (DMFCs) are easily poisoned by the intermediate species from the methanol electrooxidation. Moreover, the migration and agglomeration of Pt nanoparticles on the carbon support cause the poor durability of the catalysts over time. To solve the above problems, in this paper, the Pt-based catalyst was modified by the metal oxide CeO2 nanofibers. The main contents are as follows:Part Ⅰ:Pt/CeO2-C and Pt/Ce0.8Sm0.2O2-δ (SDC)-C catalysts were prepared by combining electrospinning technique with reduction impregnation method. The morphologies and structures of samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The electrocatalytic activity of the catalysts for methanol was measured by cyclic voltammetry, CO stripping and chronoamperometry in an acidic solution. Compared with commercial Pt/C catalyst containing the same quality percentage of Pt, Pt/CeO2-C catalyst exhibits higher electrocatalytic activity and better stability for methanol electrooxidation; Pt/SDC catalyst exbibits better anti-poisoning ability.Part Ⅱ:The catalysts with CeO2 nano fibers contents of 15 wt%,20 wt%,25 wt%,30 wt% and 35 wt% were prepared by borohydride reduction. Electrochemical tests show that when the CeO2 doping amount of 30 wt%, the catalyst exhibits superior electrocatalytic activity and long-term stability for methanol electrooxidation; when the CeO2 doping amount of 15 wt%, the catalyst exhibits superior anti-poisoning ability.Part Ⅲ:PtCo/CeO2-C catalyst with CeO2 content of 25 wt% was prepared by borohydride reduction. Compared with Pt/CeO2-C and commercial Pt/C catalysts containing the same quality percentage of Pt, PtCo/Ceo2-C catalyst exhibits superior catalytic electrocatalytic activity and stability for methanol electrooxidation.