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Artigo IPEN-doc 27790 Advancing direct ethanol fuel cell operation at intermediate temperature by combining Nafion-hybrid electrolyte and well-alloyed PtSn/C electrocatalyst2021 - DRESCH, MAURO A.; MATOS, BRUNO R.; GODOI, DENIS R.M.; LINARDI, MARCELO; FONSECA, FABIO C.; VILLULLAS, HEBE de las M.; SANTIAGO, ELISABETE I.The advancement of direct ethanol fuel cell (DEFC) represents a real challenge to electrochemical science because ethanol changes significantly the triple phase boundary properties such as the redox reactions and the proton transport. Ethanol molecules promote poor fuel cell performance due to their slow oxidation rate, reduction of the proton transport due to high affinity of ethanol by the membrane, and due to mixed potential when the ethanol molecules reach the cathode by crossover. DEFC performance has been improved by advances in the membranes, e.g., low ethanol crossover polymer composites, or electrode materials, e.g., binary/ternary catalysts. Herein, high temperature (130 °C) DEFC tests were systematically investigated by using optimized electrode and electrolyte materials: Nafion-SiO2 hybrid electrolyte and well-alloyed PtSn/C electrocatalyst. By optimizing both the electrode and the electrolyte in conjunction, DEFCs operating at 130 °C exhibited a threefold increase on performance as compared to standard commercially available materials.Artigo IPEN-doc 22409 Synthesis and performance of palladium-based electrocatalysis in alkaline direct ethanol fuel cell2016 - MORAES, L.P.R.; MATOS, B.R.; RADTKE, C.; SANTIAGO, E.I.; FONSECA, F.C.; AMICO, S.C.; MALFATTI, C.F.The present study reports the performance enhancement of alkaline direct ethanol fuel cell (ADEFC) by using non-functionalized (Vulcan) and functionalized (Vulcan-F) carbon supported Pd, PdSn, PdNi and PdNiSn anodic electrocatalysts produced by impregnationreduction method. The electrocatalysts are studied by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), and ADEFC stability tests. TGA measurements of Vulcan evidence the characteristic weight losses attributed to the presence of surface functional groups due to the acid treatment. XRD shows that a higher degree of alloying is reached between Pd and Sn, whereas the Ni in PdNi and PdNiSn exists mostly segregated in the oxide form. TEM analysis indicates an agglomeration of Pd and PdSn particles, whereas a more uniform particle distribution is observed for PdNi and PdNiSn samples. CV curves show that the onset potential is shifted towards negative values for binary and ternary samples supported on functionalized Vulcan (Vulcan-F) indicating that the ethanol oxidation is facilitated on the functionalized surface. ADEFC fuel cell tests reveal that the highest open circuit voltage and maximum power density are achieved for the PdNiSn supported on Vulcan-F in which the characterizations evidenced improved textural properties.Artigo IPEN-doc 20453 Nafion-titanate nanotubes composites prepared by in situ crystallization and casting for direct ethanol fuel cells2015 - MATOS, B.R.; ISIDORO, R.A.; SANTIAGO, E.I.; TAVARES, A.C.; FERLAUTO, A.S.; MUCCILLO, R.; FONSECA, F.C.The physical properties relevant for the application of Nafionetitanate nanotubes composites in electrochemical devices such as water absorption capacity, ion conductivity, and thermal stability are reported. The nanocomposites were prepared by in situ hydrothermal conversion of anatase into titanate nanotubes in Nafion matrix and by casting of nanotube suspensions in Nafion. Composites were characterized by differential scanning calorimetry (DSC), dynamic vapor sorption (DVS), X-ray diffraction (XRD), transmission electron microscopy (TEM), proton conductivity, and tested in direct ethanol fuel cells (DEFC). Nafion etitanate nanotubes displayed higher water retention capacity in comparison with Nafion etitania composites as revealed by DSC and DVS. The ion conductivity at intermediate temperatures (80e130 C) for Nafionetitanate nanotube composites is higher than Nafion etitania composites indicating that the hydrophilicity and conduction properties of the titanate phase contributed to the improvement of the membrane electrical properties. The Nafionetitanate nanotube composites prepared by in situ solegel exhibited improved electric and electrochemical performance at high temperatures compared to the composite prepared by casting. The combined XRD, DSC, and TEM data indicated that at RH ¼ 100% Nafionetitanate nanotubes are thermally stable up to 130 C, but for higher temperatures the titanate nanotubes are converted to rutile nanorods.