A Pt/MnV<inf>2</inf>O<inf>6</inf> nanocomposite for the borohydride oxidation reaction

Abstract

Problems associated with carbon support corrosion under operating fuel cell conditions require the identification of alternative supports for platinum-based nanosized electrocatalysts. Platinum supported on manganese vanadate (Pt/MnV2O6) was prepared by microwave irradiation method and characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, and transmission electron microscopy. The borohydride oxidation reaction (BOR) on Pt/MnV2O6 was studied in highly alkaline media using voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. BOR electrocatalytic activity of Pt/MnV2O6 was also compared with that of commercial Pt/C (46 wt% Pt) electrocatalyst. The apparent activation energy of BOR at Pt/MnV2O6 was estimated to be 32 kJ mol−1 and the order of reaction to be 0.51, indicating that borohydride hydrolysis proceeds in parallel with its oxidation. Long-term stability of Pt/MnV2O6 under BOR typical conditions was observed. A laboratory-scale direct borohydride fuel cell assembled with a Pt/MnV2O6 anode reached a specific power of 274 W g−1. Experimental results on Pt/MnV2O6 were complemented by DFT calculations, which indicated good adherence of Pt to MnV2O6, beneficial for electrocatalyst stability.