Multi-Channel WO3 Enhances Methanol Oxidation Performance of Platinum

Platinum (Pt) and Pt alloy electrocatalysts supported on carbon (Pt/C) are the best catalysts for methanol oxidation in direct methanol fuel cells (DMFC). However, their high cost hinder the commercialization of DMFC. Recently, due to the strong synergy between metal oxides and Pt, people have focused their attention on metal oxides. Among the metal oxides, tungsten trioxide (WO3) has special electrochemical properties and can be used as an electrocatalyst carrier.

Multi-channel WO3 has been impregnated on platinum to enhance its methanol oxidation performance, the result shows that the performance is better than commercial Pt/C catalyst. Herein, the multi-channel structure was replicated on WO3 through a simple one-step impregnation route and calcination process. It is proved that the prepared mc-WO3 as a carrier for methanol oxidation is a promoter. The synthesis process of Pt/WO3 catalyst is as below:

First, cut the raw materials into slices, then impregnate them with phosphoric acid solution (85wt%) and vacuum dry. Then 0.5 g of dried reed was added to 20 mL of 0.5 mM ammonium metatungstate (AMT) solution, which was prepared by dissolving 1.45 g of AMT in 1 L of deionized water. The mixture was then vacuum dried at 80°C and then heat-treated in a muffle furnace at 600°C for 60 minutes. The resulting yellow powder is referred to as mc-WO3. 10 wt% Pt/mc-WO3 was obtained by doping mc-WO3 on Pt by one-step impregnation route and calcination process.

In conclusion, reed with hierarchical structure was first used as the template to synthesize the multi-channel WO3 which was used as the electro-catalyst support. The multi-channel WO3 was then doped on platinum to enhance its performance.  The synthesized Pt/WO3 exhibit better methanol oxidation performance compared with commercial Pt/C. The morphological characterizations suggest that Pt is homogeneously dispersed on mc-WO3 with an average size of 3.3 nm. Electrochemical studies indicate that the electro-catalytic performance of the synthesized catalyst is better for methanol electro-oxidation compared with that of commercial Pt/C. This improved activity can be attributed to the enhanced H-spillover effect caused by the increased interface between Pt and WO3 in the multi-channel structure of catalysts.

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