Development of polyaniline-derived carbon materials for applications in Direct Ethanol Fuel Cells

Resumo

Three materials —PANI, PANI₈₀-NT₂₀, and PANI₅₀-NT₅₀ — were synthesized with the aim of using them as supports in anodic electrocatalysts. Mono- and bimetallic catalysts of Pt and PtRe(3) were prepared using the polyol method. Both the supports and catalysts were characterized by N₂ physisorption, thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, temperature-programmed desorption, temperature-programmed reduction, H₂ chemisorption, and benzene hydrogenation test reaction. Additionally, the catalysts were electrochemically evaluated using cyclic voltammetry, chronoamperometry, and CO stripping. Performance tests were also conducted in a prototype direct ethanol fuel cell to assess the behavior of the catalysts under conditions close to real operation. The bimetallic catalyst PtRe(3)/PANI₅₀-NT₅₀ exhibited the best performance in the three-electrode half-cell, achieving an electrochemically active surface area of 60 m² gPt^-1. Furthermore, it showed an onset potential for ethanol oxidation of 220 mV (vs Ag/AgCl) and a maximum anodic peak current of 297 mA mgPt^-1. This catalyst also demonstrated the highest performance in the prototype cell, reaching open-circuit voltage and power density values of 496 mV and 3,0 mW cm^-2, respectively.