A Pt/MnV2O6 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. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.