Atividade eletrocatalítica de nanopartículas de hexacianoferrato de rutênio para eletro-oxidação de glicerol

Abstract

In the present work, the ruthenium (III) hexacyanoferrate complex was tested for glycerol oxidation using two distinct forms of modification of the vitreous carbon electrode. In the first one, the vitreous carbon electrode was modified by electrodeposition through cyclic voltammetry at determined potential and already described in the literature, and in the second, the carbon glass electrode was modified by nanoparticles supported on Vulcan XC-72 carbon, which were synthesized by the alcohol reduction method. Subsequently, the electrocatalysts were characterized by chemical-chemical techniques and tested by electrochemical techniques. The physico-chemical characterization of ruthenium hexacyanoferrate (III) was carried out by Electron Spectrophotometry in the UV-Vis region (UV-Vis), Infrared Vibrational Spectroscopy (FTIR), Electron Transmission Electron Microscopy (TEM), Dispersive Energy X-rays (EDX) and X-ray Diffraction (XRD). Electrochemical characterization occurred by cyclic voltammetry, rotational disk electrode, chronoamperometry and electrochemical impedance spectroscopy (EIS). EDX analysis for the nanoparticles showed that the theoretical starting composition is approximately the same experimentally proven. XRD and TEM analyzes provided the size of the synthesized particles on the order of 3.8 nm, as well as the distribution and dispersion in the carbon carrier. The electrochemical results on the glycerol oxidation reaction showed that the synthesis performed by the alcohol reduction method showed an increase in electrocatalytic current when compared to the unmodified electrode. Through a study with a rotating disk electrode it was possible to verify the involvement of 3.8 electrons in the oxidation reaction of glycerol. Electrochemical impedance spectroscopy has shown that the charge transfer resistance of glycerol electro-oxidation decreases as the potential and concentration of glycerol increase. The carbon-supported ruthenium hexacyanoferrate nanoparticle-modified electrode showed an efficiency in the glycerol oxidation reaction being a viable option for use as a catalyst in direct alcohol fuel cells.