Efficient and stable PtFe alloy catalyst for electrocatalytic methanol oxidation with high resistance to CO

Abstract

Direct methanol fuel cells (DMFC) are widely considered to be an ideal green energy conversion device but their widespread applications are limited by the high price of the Pt-based catalysts and the instability in terms of surface CO toxicity in long-term operation. Herein, the PtFe alloy nanoparticles (NPs) with small particle size (∼4.12 nm) supported on carbon black catalysts with different Pt/Fe atomic ratios (Pt1Fe2/C, Pt3Fe4/C, Pt1Fe1/C, and Pt2Fe1/C) are successfully prepared for enhanced anti-CO poisoning during methanol oxidation reaction (MOR). The optimal atomic ratio of Pt/Fe for the MOR is 1:2, and the mass activity of Pt1Fe2/C (5.40 A mg−1Pt) is 13.5 times higher than that of conventional commercial Pt/C (Pt/C-JM) (0.40 A mg−1Pt). The introduction of Fe into the Pt lattice forms the PtFe alloy phase, and the electron density of Pt is reduced after forming the PtFe alloy. In-situ Fourier transform infrared results indicate that the addition of oxyphilic metal Fe has reduced the adsorption of reactant molecules on Pt during the MOR. The doping of Fe atoms helps to desorb toxic intermediates and regenerate Pt active sites, promoting the cleavage of C–O bonds with good selectivity of CO2 (58.1%). Moreover, the Pt1Fe2/C catalyst exhibits higher CO tolerance, methanol electrooxidation activity, and long-term stability than other PtxFey/C catalysts.