ORR Activity and Direct Ethanol Fuel Cell Performance of Carbon-Supported Pt−M (M = Fe, Co, and Cr) Alloys Prepared by Polyol Reduction Method

Abstract

A polyol reduction method is employed to prepare carbon-supported Pt and Pt−M (M = Fe, Co, and Cr) alloy catalysts by simultaneous reduction and decomposition of metal precursors with 1,2-hexadecanediol in the presence of nonanoic acid and nonylamine protecting agents. The prepared materials are characterized by powder XRD, HRTEM, and EDX. The face-centered cubic structure of Pt in the prepared materials is evident from XRD. Good dispersion of Pt and Pt alloy nanoparticles on the carbon support is seen from the high-resolution TEM images. The presence of respective elements with controlled composition is observed from EDX analysis. Electrochemical performance of the prepared materials is investigated by cyclic voltammetry and tested in a single-cell DEFC. The inhibition of formation of (hydr)oxy species on the Pt surface by the presence of alloying elements is observed. Oxygen reduction activity of the Pt−M/C (M = Fe, Co, and Cr) is found to be ∼1.5 times higher than that of the as-synthesized and commercial Pt/C catalysts. Single-cell DEFC tests indicated the good performance of Pt−M/C (M = Fe, Co, and Cr) compared with that of the as-synthesized and commercial Pt/C catalysts. The DEFC performance increased in the order Pt/C comm < Pt/C as-syn < Pt−Fe/C < Pt−Co/C ∼ Pt−Cr/C. Stability under DEFC operating conditions for 50 h indicated the good stability of Pt alloys compared with that of Pt catalysts.