| Résumé | Several Pd-composite Nb 0.06Ti 0.94O 2 materials are synthesized by a two-step procedure, and employed as the Pt-Pd alloy catalyst support for the PEM fuel cell oxygen reduction reaction (ORR). These supports and their supported catalysts are characterized using analytical and electrochemical methods with respect to their material morphology, chemical/electrochemical stability, electronic conductivity as well as oxygen reduction reaction (ORR) mass activity/stability. For the supported Pt-Pd catalysts, the Pt-Pd nanoparticles adhered to both the Nb 0.06Ti 0.94O 2 and composited Pd surfaces to form Pt mPd n clusters. A possible synergetic interaction between the Pt-Pd alloy catalyst and its Pd-Nb 0.06Ti 0.94O 2 composite support is believed to exist which enhances the ORR activity of these catalysts. The electronic conductivity of Nb 0.06Ti 0.94O 2 can be greatly improved after forming composites with Pd to the desired levels required for electrocatalyst applications. Three supported Pt-Pd catalysts, 20 wt% Pt 0.62Pd 0.38/Pd 10wt%-(Nb 0.06Ti 0.94O 2) 90wt%, 20 wt% Pt 0.62Pd 0.38/Pd 30wt%-(Nb 0.06Ti 0.94O 2) 70wt%, and 20 wt% Pt 0.62Pd 0.38/Pd 50wt%-(Nb 0.06Ti 0.94O 2) 50wt%, are synthesized and tested using both cyclic voltammetric and rotating disk electrode techniques with respect to their surface electrochemistry, ORR mass activity, and electrochemical stability. All three catalysts show higher Pt mass activity (>130 mA mg Pt -1 at 0.9 V vs. RHE) than that of the baseline 47 wt% Pt C -1 carbon supported catalyst (110 mA mg Pt -1). However, the durability of these catalysts needs to be further improved. |
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