Investigação da Eficiência de Eletro-conversão de Etanol para CO2 em Temperatura Intermediária Utilizando Aquivion® como Eletrólito

The C-C bond cleavage has been the limiting factor for the development of direct ethanol fuel cells, since this step is fundamental for the complete ethanol electroconversion to CO2 or for higher efficiency of CO2 formation throughout the ethanol oxidation reaction (EOR). Thus, more selective catalysts for the complete EOR is the central challenge The study of the EOR at intermediate temperature can be an alternative to accelerate the reaction kinetics of the C-C bond breakage. On the base of these facts, in this work, nanoparticles of Rh/C, Sn/Pt/C (1:3), and Sn/(PtRh)/C (1:3) were synthesized using the impregnation method followed by thermal treatment, and they were physically characterized by XRD, X-EDS, TEM and XANES. At room temperature, the electrochemical experiments in potentiostatic mode showed low current efficiencies (< 1%) for the EOR to CO2 on all nanomaterials, which was attributed to the catalytic surface poisoning by adsorbed CO and CHx species. On the other hand, studies at intermediate temperature (120 ºC), Fig. 1, using an Aquivion® E87-12S short-side-chain perfluorosulfonic membrane, showed an increase in the average of current efficiencies to CO2 formation, and the ionic signal for CO2 remained constant, for all nanoparticles, mainly for Rh/C. This electrocatalyst presented the highest CO2 electro-conversion efficiency (54,95 %), followed by Pt/C (31,21 %), Sn/(PtRh)/C (1:3) (30,28 %), and Sn/Pt/C (1:3) (10,21 %). In this way, the combination of the increased reaction temperature (120 ºC) and the use of of Rh, showed an unprecedented high faradaic efficiency of ethanol electroconversion to CO2.