Abstract

Here, a new functionalization method is introduced to control deposition of Pt nanoparticles on reduced graphene oxide (rGO). In this paper, we investigate the heterogeneous deposition of nanometer-sized Pt islands on rGO subjected to oxidation prior to deposition in the same conditions. We demonstrate that functional groups act as nucleation sites for Pt nanoparticle, and that homogeneous nucleation of small particles can be achieved by combining surface functionalization with diazonium chemistry and appropriate stabilizers in solution. For the purposes of this study, an effective electrochemical mediator is prepared using 4-aminothiophenol-modified rGO as a support decorated with Pt nanoparticles (Pt^@SC₆H₄–rGO) for the oxidation of methanol and reduction of oxygen. The surface morphology and composition of Pt^@SC₆H₄–rGO and Pt^@rGO as well as their activity toward methanol oxidation and oxygen reduction are investigated by atomic force microscopy, field emission scanning electron microscopy, X–ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The results show that decoration of Pt nanoparticle on functionalized rGO leads to three-dimensional Pt nanostructures. Comparisons of the synthesized Pt@rGO and Pt@SC₆H₄–rGO in terms of their electrochemical performance also show that, compared to Pt^@rGO, Pt^@SC₆H₄–rGO has a better electrocatalytic activity for methanol oxidation and oxygen reduction in a solution containing 0.5 mol L⁻¹ H₂SO₄ and/or 1.0 mol L⁻¹ methanol.