| Popis: |
Fabrication of agglomeration-free Pt-based bimetallic nanoparticles (NPs) supported on carbon structures is extremely important for direct methanol fuel cells (DMFCs) applications. In this study, by introducing halide ions and ascorbic acid (AA) as a reducing agent in the synthesis recipe a controlled co-reduction of graphene oxide sheets, H2PtCl6 and Na2PdCl4 is achieved. The microstructure and morphological features of fabricated Pt–Pd bimetallic NPs deposited on reduced graphene oxide (RGO) sheets, herein after called as Pt–Pd/RGO bimetallic nanocomposites (NCs), are evaluated by X-ray diffraction and transmission electron microscopy. The results reveal that for the samples prepared in the presence of halide ions (i.e. Pt–Pd/RGO-5KI and Pt–Pd/RGO-15KI) the uniformity and dispersion of Pt–Pd bimetallic NPs are significantly improved on RGO sheets over the sample prepared in the absence of halide ions (i.e. Pt–Pd/RGO-0KI). The electrocatalytic activities of Pt–Pd/RGO bimetallic NCs towards methanol oxidation are investigated by cyclic voltammetric and chronoamperometric measurements. Among the various Pt–Pd/RGO bimetallic NCs prepared, Pt–Pd/RGO-15KI exhibits the best electrocatalytic activity and stability for methanol oxidation. The improved methanol oxidation on Pt–Pd/RGO-15KI is due to the enhanced uniformity, dispersion and lower size of Pt–Pd NPs, and synergistic roles played by Pt, Pd and the RGO support. The present halide-aided fabrication strategy will be significantly helpful to the further design of Pt-based nanocomposites with desired properties relevant to DMFCs applications. |
