(204d) Molybdenum Carbide Based Electrocatalysts for PEM Fuel Cells

Fuel cells have been highly regarded as an alternative power source in the future. Among several types of fuel cells, the proton exchange membrane (PEM) fuel cell has gained interest for use in automotive, stationary and portable applications because of it's high power density, clean emissions, low temperature, etc.. Since Pt-based electrocatalysts are used widely, the cost to produce and commercialize PEM fuel cells is high[1]. Therefore, reducing the amount of Pt usage or developing an inexpensive catalyst are essential in PEM fuel cells research.

Transition metal carbides have been reported to have Pt-like chemical activities and electronic properties[2,3], particularly Mo2C. There have been many studies related to the development of transition metal carbides for use as electrocatalysts[4], and they show much promise to be a potential substitutes for Pt catalysts.

In this study, Mo2C/Vulcan (VC) was used as an oxygen reduction reaction (ORR) electrocatalyst for PEM fuel cells. A series of Mo2C/VC catalysts with different carbide loadings were prepared by temperature programmed reaction and wet impregnation methods. Additionally, another series of catalysts were prepared with 5% Mo2C/VC and metal loading of a second metal: Pt, Pd, W, etc.. The catalysts were characterized by BET and X-ray diffraction (XRD). The electrocatalytic activity for ORR was evaluated in a single fuel cell in addition to using cyclic voltammetry.

The results showed that Mo2C was synthesized on VC and the two series of catalysts had electrocatalytic activity for ORR. Among the catalysts with different carbide loadings, the electrocatalytic activity of 5% Mo2C/VC catalyst was the highest. The performance was improved by loading additional metals on 5% Mo2C/VC catalysts, loading Pd and W showed the best improvement.