PtRu/Carbon Hybrids With Different Pt:Ru Atomic Ratios Prepared by Hydrothermal Carbonization for Methanol Electro-Oxidation

Abstract

PtRu/Carbon hybrid materials with different Pt:Ru atomic ratios (50:50, 60:40, 80:20 and 90:10) and 5 wt% of nominal metal loading were prepared by hydrothermal carbonization at 200°C using H2PtCl6.6H2O and RuCl3.xH2O as metals sources and catalysts of the carbonization process and starch as carbon source and reducing agent. The obtained materials were further treated at 900 oC under argon and characterized by energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and cyclic voltammetry. The electro-oxidation of methanol was studied by cyclic voltammetry and chronoamperometry. The PtRu/Carbon materials showed Pt:Ru atomic ratios obtained by EDX similar to the nominal ones. XRD analysis showed that PtRu face-cubic centered (fcc) alloy and Ru hexagonal close-packed (hcp) phases coexist in the obtained materials. The average crystallite sizes of the PtRu (fcc) alloy phase were in the range of 10-12 nm. The material prepared with Pt:Ru atomic ratio of 50:50 showed the best electroactivity for methanol electro-oxidation.