Nanoeletrocalisadores de PdxNby/C para reação de eletrooxidação de etanol

Direct ethanol fuel cells have been evaluated as a possible alternative source of sustainable energy, because ithas a high current density and minimal pollutant production [1]. However, ethanol oxidation reactionEORresulting in only H2O and CO2has beenagreat challengefor the technology. The important limitationfactors of the reaction arethe breaking of the C-C bond and the intermediatesformation that block the active sites of the electrocatalyst [2]. PdxNby/C binary electrocatalysts inthe metal mass ratio(1: 0; 1: 1; 1: 3; 3: 1; 0: 1) supported on Vulcan XC-72 carbon (20% wt) were prepared by thesol-gel method. The materials were characterized by Transmission Electron Microscopy (TEM), Energy Dispersive X-raySpectroscopy(EDX), X-ray Diffraction (XRD) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).The electrochemical activity for ethanol electrooxidation reaction (EOR) of the prepared nanoeletrocatalysts was studied by Cyclic Voltammetry (CV) andChronoamperometry (CA), versus SCE reference electrode and Pt wire counter electrode. The results of these experiments are shown in Table 1. The current density peak for EOR using Pd1Nb1/C is2.86 times higher than the commercial Pd/Cfor the same process, 45.5 and 15.9 mAmg-1Pdrespectively.Pd1Nb1/C also has the lowest onset potential for EOR. These results suggest that Pd1N1/C is better forEOR thanPd/C due to the presence of Niobium in the electrocatalyst.We propose that Nb decreasesthe poisoning onPdsurfaceby CO due to the bifunctional mechanism, where Nb supplies oxygenated species to the active sites of the Pd with adsorbed CO forCO oxidation[3].Electronic effect cannot be discarded.