Comparison of Electrocatalytic Properties of PtCo/Graphene Catalysts for Ethanol, Methanol and Borohydride Oxidation

In this study the graphene supported PtCocatalysts (denoted as PtCo/GR) with diferent molar ratios of Pt and Co were fabricated by means of the rapid microwave heating method with the aim to use them in an alkaline fuel cells, using ethanol, methanol and borohydride as fuel.The synthesized catalysts were examined by Transmission Electron Microscopy, X-ray Ddiffraction and Inductively Coupled Plasma Optical Emission Spectroscopy. The electrochemically active surface areas of the prepared catalysts were determined from the cyclic voltammograms of the different PtCo/GR catalysts recorded in a deaerated 0.5 M H₂SO₄ solution at a sweep rate of 50 mV s^–1 by calculating the charge associated with the hydrogen adsorption (220 µg cm^-2). The electrocatalytic activitiy of the synthesized catalysts was investigated towards the oxidation of ethanol, methanol and borohydride in an alkaline medium by means of cyclic voltammetry and chronoamperometry.

It was found that the PtCo/GR catalysts with an average particle size of ca. 1-3 nm were synthesized by means of microwave heating of Pt(IV) and Co(II) salts in ethylene glycol solutions. The synthesized PtCo/GRcatalysts with the different Pt:Co molar ratios show an enhanced activity towards the oxidation of H₂ generated by catalytic hydrolysis of BH₄^– and direct oxidation of BH₄^– ions as well as methanol and ethanol oxidation as compared with that at the graphene supported bare Co and Pt catalysts. It should be noted that the electrocatalytic activity of the PtCo/GR catalysts depends on the molar ratio of Pt:Co in the catalysts and type of fuel.