Investigation of CeO2/Graphene and Nb2O5/Graphene Supported Pt and PtCo Catalysts Towards Methanol and Ethanol Oxidation and Oxygen Reduction Reactions

Abstract

In this study the CeO2/graphene and Nb2O5/graphene supported Pt and PtCo catalysts denoted as PtCeO2/GR, PtNb2O5/GR, PtCoCeO2/GR and PtCoNb2O5/GR were prepared by polyol method using the simple and rapid microwave heating method. To obtain the catalysts, required amounts of CeO2/graphene or Nb2O5/graphene, H2PtCl6 and CoCl2 were heated in ethylene glycol at 170 oC for 30 min in the microwave reactor. It was found that Pt nanoparticles were successively deposited onto the surfaces of CeO2/graphene and Nb2O5/graphene. For comparison, the PtCo/graphene (PtCo/GR) and Pt/carbon (Pt/C) catalysts were prepared in the same manner. The composition and morphology of catalysts were detected by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). The synthesized PtCeO2/GR, PtNb2O5/GR, PtCoCeO2/GR, PtCoNb2O5/GR, PtCo/GR and Pt/C catalysts were examined as electrocatalysts towards the electro-oxidation of methanol and ethanol, and the reduction of oxygen. It has been found that the CeO2/GR or Nb2O5/GR supported Pt and PtCo catalysts show an enhanced electrocatalytic activity towards the oxidation of ethanol and methanol in an alkaline medium as compared with that of the Pt/C catalyst. Depending on catalysts composition, ethanol and methanol oxidation current densities were found to be ca. 3 – 12 times higher at the CeO2/GR and Nb2O5/GR catalysts, respectively, in comparison with those at the Pt/C catalyst. In the case of oxygen reduction, the PtCoCeO2/GR and PtCoNb2O5/GR catalysts outperform the PtCeO2/GR, PtNb2O5/GR, PtCo/GR and Pt/C catalysts towards oxygen reduction and shows higher onset potential, as well as higher current density towards the oxygen reduction reaction as compared with those at the aforementioned catalysts.