Electrochemical activity and stability of core–shell Fe2O3/Pt nanoparticles for methanol oxidation

Abstract

Core–shell Fe2O3/Pt nanoparticles with amorphous iron oxide cores are successfully synthesized by a two-step chemical reduction strategy. The Pt loading can be adjusted using this preparation technique to obtain a series of chemical compositions with varying amounts of Pt precursors. The morphology, structure, and composition of the as-prepared nanoparticles are characterized by transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. Electrocatalytic characteristics are systematically investigated by electrochemical techniques, such as cyclic voltammetry, chronoamperometry, and in situ Fourier transform infrared spectroscopy. Compared with the E-TEK 40 wt% Pt/C catalyst, the as-made Fe2O3/Pt nanoparticles exhibit superior catalytic activity with lower peak potential and enhanced CO2 selectivity toward methanol electrooxidation in acidic medium. The highest activity is achieved by core–shell Fe2O3/Pt nanoparticles with a Fe/Pt atomic ratio of 2:1 (A g−1 of Pt) or 3:1 (mA cm−2). These nanomaterials also show much higher structural stability and tolerance to the intermediates of methanol oxidation. Methanol electrooxidation reactions with higher performance can be achieved using core–shell nanoparticles with an amorphous iron oxide core and minimum Pt loading.