Synthesis and characterization of highly active Pbx@Pty/C core-shell nanoparticles toward glycerol electrooxidation

Abstract

In this manuscript we report the facile synthesis route and electrochemical evaluation of Pbx@Pty/C core–shell (CS) nanostructures (with x:y molar ratios of 1:3, 1:2, 1:1 and 2:1) for glycerol electrooxidation reaction in acid media. PbxPty/C alloy nanoparticles were also synthesized with the same compositions of CS nanoparticles for comparative purposes. The as-prepared Pbx@Pty/C nanostructures were characterized by scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Microscopy results indicate that CS nanoparticles were well-dispersed on carbon support, with spherical shapes and small particle sizes (2.6–3.9nm). Deviations in the lattice parameter, as well as, in binding energies demonstrated interaction between Pt and Pb, leading to alterations of the surface atom electron densities that, in turn, influence the Pbx@Pty/C electroactivity. High-angle annular dark-field-STEM associated with line-scan energy dispersive X-ray spectroscopy indicate the formation of a core–shell type structure (Pt shell and Pb core) for the Pb@Pt3/C composition, which is in good agreement with the cyclic voltammetry (CV) experiments, where only the characteristic profile of polycrystalline Pt is observed. The catalytic activity towards glycerol oxidation was accessed by CV, chronoamperometry and quasi-stationary potentiostatic polarization. The CS nanostructures showed higher catalytic activities than those of the nanostructured alloys with similar chemical compositions, probably due to different surface structures combined with electronics effects. Moreover, the investigated CS nanostructures presented good durability. These results credited Pb@Pt3/C CS nanoparticles as potential catalysts in direct glycerol fuel cells (DGFC). Finally, we highlight that the investigated synthesis route is a facile and reproducible way for producing Pbx@Pby/C CS electrocatalysts, which is significant for the development of high performance DGFC.