MoC–graphite composite as a Pt electrocatalyst support for highly active methanol oxidation and oxygen reduction reaction

Abstract

Molybdenum carbide (MoC or Mo₂C) nanoparticles down to 2 nm in size on carbon (C–Mo_xC) are synthesized through an ion exchange process, and used as a Pt electrocatalyst support for both the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). XRD, Raman spectrometer, TEM and XPS measurements are used to characterize the structure and properties of the synthesized materials. The results show that the typical Pt/C–MoC exhibits 160 mV negative shift in onset potential for the MOR, and 2.3 times kinetic mass current (276.7 mA mg_Pt⁻¹) for the ORR compared to commercial Pt/C-TKK. The large improvement in the catalytic activity resulted from the synergistic effect and binding effect between Pt and MoC. The results also show that MoC promotes both the activity and stability of the Pt electrocatalyst to a greater extent than Mo₂C, owing to the different synergistic effect and binding energy. In addition, the Mo compound was found to have an obvious catalytic effect on the graphitization of the carbon source, and the graphited carbon was supposed to give more stability as an electrocatalyst support.