Platinum nanoflowers decorated three-dimensional graphene–carbon nanotubes hybrid with enhanced electrocatalytic activity

Abstract

A three-dimensional carbon electrode, in the form of vertically grown multiwalled carbon nanotubes (MWNTs) on a single layer graphene floor (G-MWNTs) is synthesized by one-step chemical vapor deposition (CVD) method, as supporting material for platinum (Pt) electrocatalyst. Nanostructured Pt catalyst is electrodeposited onto this 3D-carbon electrode and their structural and electrochemical properties are investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy. The electrocatalytic performance of the modified electrode (Pt/G-MWNTs) towards methanol oxidation is also investigated by CV. Experimental results demonstrate an enhanced efficiency of the G-MWNTs hybrid film, as Pt catalyst support, for methanol oxidation in comparison to pristine single layer graphene electrode with regard to electroactive surface area, forward anodic peak current density, onset oxidation potential, diffusion efficiency and the ratio of forward to backward anodic peak current density (If/Ib). This enhanced electrochemical and catalytic performance towards methanol oxidation is attributed to the high surface area of three-dimensional G-MWNTs hybrid film due to synergistic combination of both structural and electrical properties of 2D-graphene and 1D-MWNTs, allowing higher dispersion of Pt.