Core–shell structured PtRu nanoparticles@FeP promoter with an efficient nanointerface for alcohol fuel electrooxidation

Abstract

In this study, a bottleneck was overcome for direct alcohol fuel cells using state-of-the-art PtRu catalysts for alcohol fuel oxidation. Herein, a core–shell structured PtRu catalyst system based on the emerging promoter FeP was developed that showed excellent catalytic performance for the oxidation of alcohol fuels. The surface spectrometric analysis and morphology observation confirmed the formation of a nanointerface of the PtRu shell and FeP core hybrid catalyst (PtRu@FeP), and efficient ligand effects and electronic effects were found to result from the noble metal active sites and adjacent promoter in the core–shell structure. The facile formation of oxygen-containing species and the strong electronic effects could activate the Pt active sites, leading to high catalytic performance. High anti-CO poisoning ability was found for this catalyst system when compared with the case of the benchmark commercial PtRu/C catalyst (110 mV less and 60 mV less as evaluated by the peak and onset potentials for CO oxidation, respectively). The PtRu@FeP catalysts also exhibited much higher catalytic activity and stability when compared with commercial and home-made PtRu/C catalysts; specifically, the peak current density of the PtRu@FeP 1 : 1 catalyst was about 2 and 3 times higher than those of the commercial PtRu/C catalyst and home-made PtRu/C for the oxidation of the alcohol fuels methanol and ethanol; moreover, high catalytic efficiency, improved by 2 times, was found, as expressed by the specific activity. Excellent catalytic stability as evaluated by 1000 cycles of cyclic voltammetry measurements was also demonstrated for the PtRu@FeP catalysts. The high catalytic performance could be attributed to the intimate nanointerface contact of the core–shell structured PtRu shell over the FeP core via a bi-functional catalytic mechanism and electronic effects based on the ligand effect in this catalyst system. The current study is a significant step to increase the PtRu catalytic performance via nanointerface construction by a core–shell structure on a novel promoter for direct alcohol fuel cells.