Platinum nanoparticles supported on electrochemically oxidized and exfoliated graphite for the oxygen reduction reaction

Electrochemically oxidized graphite oxide (eGO) was prepared by electrochemical oxidation of graphite electrodes in 1 M H2SO4 solution as electrolyte. The eGO was used as support of Pt nanoparticles (Pt-NPs) for the synthesis of Pt/rGO (reduced GO from eGO) catalyst using a simple chemical reduction method of metal salt precursor. The structural and morphological characteristics of the eGO, Pt/rGO, Pt/OVC (using oxidized Vulcan carbon) and Pt/Graphite (using pristine graphite) electrocatalysts were investigated through X-ray diffraction (XRD), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Scanning Transmission Electron Microscopy (STEM), Scanning Electron Microscopy (SEM), BET area analysis and Electrochemical Impedance Spectroscopy (EIS). The effect of the support's oxidation conditions in the catalytic response of Pt-NPs towards the oxygen reduction reaction (ORR) in acid media was studied through the rotating disk electrode (RDE) technique. STEM micrographs showed a good distribution of Pt-NPs on the rGO support with some regions of Pt-NPs agglomeration, but in lower degree compared with Pt/OVC catalyst. RDE measurements confirmed higher specific activity and higher mass activity of the Pt/rGO compared to the Pt/OVC and Pt/Graphite catalysts used as reference materials. Stability test after 10,000 sweeps of cyclic potential by accelerated electrochemical degradation, showed better durability for Pt/rGO catalyst compared with Pt/OVC in terms of ORR activity. Single fuel-cell performance studies for membrane electrode assemblies (MEAs), prepared with the Pt/rGO as cathode, showed that the maximum power density reached was 56.3 mW mgPt(-1) cm(-2) using a total Pt load of 0.12 mg Pt/cm(2). (C) 2018 Elsevier Ltd. All rights reserved.