Preparation of Pt–Sn/graphene catalysts and their activities for ethanol electrooxidation in polyol synthesis

Pt–Sn/graphene catalysts were prepared by heat treatment of a dispersion of graphene oxide, SnCl2 and H2PtCl6 in ethylene glycol at 130 °C for 3 h after its pH value had been adjusted to 12 by NaOH, followed by centrifuging, washing with ethanol and water, and cryodrying. The pH value of the heat-treated dispersion was controlled by adding dilute nitric acid to 2, 4 and 6 to mediate the properties of the catalysts and its effects on the compositions, microstructure and catalytic activities of the resulting catalysts in ethanol electrooxidation. These were investigated by XRD, ICP, TEM and cyclic voltammetry. Results indicated that with decreasing pH values the Sn content increased, the Pt/Sn atom ratio decreased and the electrochemical activity increased. The current density for ethanol electrooxidation was increased by 120% at the pH value of 2 compared for the sample without nitric acid. The improvement of the catalytic activity can be ascribed to an increased loading of Sn and Pt since the oxidative product of ethylene glycol in the heat treatment acted as a chelating agent for metal nanoparticles under high pH values. arbon Materials 2014, 29(3): 231–235]