In this work we studied the effect of the composition and thermal treatment in H2 of Pt-Rh/C materials with atomic ratios close to Pt:Rh 3:1, 1:1 and 1:3 and metal loading of 40 wt. %, for the COads and ethanol oxidation. Catalysts were prepared by chemical reduction with formic acid and physically characterized by energy dispersive X-rays spectroscopy (EDX), electron backscattering (EBS) and transmission electron microscopy (TEM), showing Pt:Rh ratios close to the nominals values, similar average particle sizes and an appropriated distributions of metal on carbon support at micro and nano scale. Cyclic voltammetry experiments showed a surface enriched in Pt due to the termodinamically unstable Pt-Rh system at the experimental temperature. The currents were normalized using the charge of oxidative desorption of CO allowing to observe differences among the current levels generated exclusively by the Rh electronic effects on the Pt. The thermal treatments of the Pt-Rh catalysts in a hydrogen atmosphere showed greater stability of the materials and notorious increases of the current levels for CO and ethanol electro-oxidation reactions. This suggests the necessity of better exploring the effects of thermal treatments in the electrocatalysis of the ethanol oxidation reaction.
Pt-Rh/C; thermal treatment (TT); CO electro-oxidation; ethanol electro-oxidation
