Electrocatalytic Performance of PtSn/C-In2O3 center dot SnO2 Nanoparticles Prepared by Sodium Borohydride Reduction Process for Ethanol Oxidation in Acidic and Alkaline Electrolytes

PtSn/C-In2O3 center dot SnO2 electrocatalysts were prepared by the borohydride reduction method in the single step using H2PtCl6 center dot 6H(2)O and SnCl2 center dot 2H(2)O as metal sources, sodium borohydride as reducing agent and a physical mixture of 85% Vulcan Carbon XC72 and 15% In2O3 center dot SnO2(indium tin oxide - ITO) as support. PtSn/C-In2O3 center dot SnO2 electrocatalysts were characterized by X-ray diffraction (XRD), energy dispersive analysis (EDX), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperommetry (CA) and polarization curves in alkaline and acidic electrolytes (single cell experiments). The diffractograms of PtSn/C-In2O3 center dot SnO2 electrocatalysts showed peaks associated to the face-centered cubic (fcc) structure of platinum, peaks which could be identified as a cassiterite SnO2 phase or with Indium-doped SnO2(ITO) used as supports. TEM micrographs showed metal nanoparticles with average nanoparticle size between 2.4 and 2.7 nm. Ethanol oxidation in acidic and alkaline electrolytes was investigated at room temperature, by chronoamperommetry (CA), where PtSn/C-In2O3 center dot SnO2(70:30) showed the highest activity among all electrocatalysts in study considering ethanol oxidation for acid electrolyte, while for alkaline electrolyte the highest activity was observed for PtSn/C-In2O3 center dot SnO2(50:50). Polarization curves at 100 degrees C showed PtSn/C-In2O3 center dot SnO2(70:30) with superior performance for ethanol oxidation for acidic electrolyte and PtSn/C (70:30) for alkaline electrolyte, when compared to Pt/C for both electrolytes. The best performance obtained by PtSn/C-In2O3 center dot SnO2(70:30) in real conditions could be associated with the occurrence simultaneously of the bifunctional mechanism and electronic effect resulting from the presence of PtSn alloy or a synergetic effect between PtSn and In2O3.