RODRIGO FERNANDO BRAMBILLA DE SOUZA
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Artigo IPEN-doc 28133 New approach by electrospray technique to prepare a gas diffusion layer for the proton exchange membrane fuel cell anode2021 - SILVA, L.M.G.; LEOCADIO, G.N.; SOUZA, R.F.B. de; MIERZWA, J.C.; DUONG, A.; VENANCIO, E.C.; NETO, A.O.The performance of the electrospray technique was applied to obtain a gas diffusion layer (GDL) for a proton exchange membrane fuel cell. It was confirmed by confocal microscopy that polytetrafluorethylene (PTFE) was impregnated into the backbone, forming a dispersed layer of microscopic size homogeneously distributed over the substrate. The PTFE layer was characterized by infrared spectroscopy and thermogravimetric analysis. In this work, we demonstrated that the use of the GDL prepared by electrospray increases the maximum power of the H2/O2 fuel cell by about 10% and decreases the diffusion loss of the electrode owing to a better distribution characteristic hydrophobic coating with low impedance to gas diffusion. Thus, our method is promising for the development of fuel cells by the production of diffusion layers.Artigo IPEN-doc 28132 Facile, clean and rapid exfoliation of boron-nitride using a non-thermal plasma process2021 - SOUZA, RODRIGO F.B. de; MAIA, VICTORIA A.; ZAMBIAZZI, PRISCILLA J.; OTUBO, LARISSA; LAZAR, DOLORES R.R.; NETO, ALMIR O.Non-Thermal Plasma source was used in this work to exfoliated boron-nitride (BN) powders. The generation of hexagonal BN nanosheets (h-BNNSs) few-layered was observed by TEM. The hBN exfoliation occurred along their transverse axis, preserving the hexagonal structure. The micrographs showed ordered lattice fringes with d-spacing of approximately 0.33 nm indicating the increase of (0 0 2) h-BNNSs crystal lattice planes, also confirmed by the relative peak intensity decrease in relation to the other peaks in XRD measures. The few amounts of layers were confirmed by intensity decrease, enlargement, and blue shift of E2 g vibrational mode in Raman spectra. Moreover, the appearance of the FTIR band corresponding to the hydroxyl group occurs due to large amounts of defects such as vacancy defects.Artigo IPEN-doc 27171 Au core stabilizes CO adsorption onto Pd leading to CO2 production2020 - FONTES, E.H.; NANDENHA, J.; SOUZA, R.F.B. de; ANTONIO, F.C.T.; HOMEM-DE-MELLO, P.; NETO, A.O.Au core and Pd shell supported on carbon structure Au@Pd/C can cleave the CeC bond of ethanol molecules leading to the production of a relatively high amount of CO2 when compared with Pd/C electrocatalyst as the attenuated total reflectance - Fourier transform infrared (ATR-FTIR) experiment shows. Density functional theory (DFT) calculations showed that this could be explained by the oxidation of CO species adsorbed into Pd sites that has a modified electronic structure compared with Pd/C. In terms of DFT analysis, the highest thermodynamical stability of CO in Pd shell with Au core atoms, when compared with Pd/C is because of the increase of virtual orbital states near Fermi level that can be occupied by valence electrons of CO molecule. The d-band center shift is experimentally verified using the valence band X-ray photoelectron spectroscopy and theoretically predicted by the Generalized Koopmans’ Theorem. Besides that, Au@Pd/C electrocatalyst has a better electrochemical activity when compared with Pd/C.