Pt nanoflower/graphene-layered composites by ZnO nanoparticle expansion of graphite and their enhanced electrocatalytic activity for methanol oxidation

Pt nanoflowers (NFs) with uniform size and high dispersion have been inserted between sheets of graphene through a three-step protocol consisting of ZnO nanoparticle (NP) expansion of graphite, electrochemical deposition of PtCl62−, and dissolution of the ZnO NPs. The key synthesis strategy employs ZnO NPs as the insertion to increase the graphite interlayer distance for insertion of PtCl62− but avoid the preparation of graphene oxides (GOs) and further reduction processes. The resulting Pt NF/graphene-layered composites are characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectra. The results show that highly dispersed Pt NFs with a uniform size of 250 nm insert between the graphene sheets and exhibit significantly higher electrocatalytic activity and better stability for the oxidation of methanol compared to Pt NFs deposited on the surface of graphite and GOs. These attractive features are a result of the layered structure consisting of alternating highly dispersed Pt NFs with high surface area and graphene with high conductivity. Our work provides a new route for the preparation of Pt NF/graphene-layered composites, which are promising electrocatalysts for direct methanol fuel cells.