JULIO NANDENHA
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Artigo IPEN-doc 28670 CO2 reduction on Cu/C used as a cathode in a polymeric electrolyte reactor2022 - LIMA, MARIANA; GODOI, CAMILA M.; SANTOS, MONIQUE C.L.; NANDENHA, JULIO; NETO, ALMIR O.; SOUZA, RODRIGO F.B. deCO2 is one of the leading greenhouse gases, so studies that turn this gas into higher value-added products, that function as simpler and cheaper hydrogen stores, as an alcohols, are extremely important. In this work we using a polymeric Electrolyte Reactor– fuel cell type supplied with H2 on platinum anode and dry CO2 in the cathode with a copper-carbon electrocatalyst. Copper nanoparticles supported on carbon Vulcan XC72 were produced by the sodium borohydride reduction method. The XRD revealed the presence of two different phases, CuO and Cu2O. In addition, the TEM images revealed agglomerates presence. The water, formaldehyde, methanol, methane, formic acid, dimethyl ether, oxalic acid, dimethyl carbonate, and ethylene-glycol were observed by differential mass spectroscopy on line with the reaction and the onset potential for each product and these results were confirmed by infrared spectroscopy – ATR-FTIR setup. This work showed the mapping CO2 reduced compounds for onset potential proposing some contributions to the literature.Artigo IPEN-doc 27383 High CO tolerance of Pt nanoparticles synthesized by sodium borohydride in a time-domain NMR spectrometer2020 - RAMOS, A.S.; SANTOS, M.C.L.; GODOI, C.M.; QUEIROZ, L.C. de; NANDENHA, J.; FONTES, E.H.; BRITO, W.R.; MACHADO, M.B.; NETO, A.O.; SOUZA, R.F.B. deThe CO poisoning effect was overcome using a novel synthesis method. This method consists of using sodium borohydride reducing agent assisted by magnetic field and radiofrequency pulses in the time-domain NMR spectrometer. This synthesis was useful to disperse the Pt nanoparticles over the carbon support and to compress the lattice strain of the Pt crystalline structure. Besides that, Pt/C MFP90° showed a multi-CO oxidation component in cyclic voltammetry, and this can avoid the poisoning effect by creating a large availability of CO species to be adsorbed, desorbed, and re-adsorbed. Pt/C MFP90° has also shown the best performance in the PEMFC regarding H2 and CO + H2 experiments.Artigo IPEN-doc 25731 Methanol oxidation in acidic and alkaline electrolytes using PtRuIn/C electrocatalysts prepared by borohydride reduction process2018 - SANTOS, M.C.L.; NANDENHA, J.; AYOUB, J.M.S.; ASSUMPÇAO, M.H.M.T.; NETO, A.O.PtRuIn/C electrocatalysts (20% metal loading by weight) were prepared by sodium borohydride reduction process using H2PtCl66H2O, RuCl3xH2O and InCl3xH2O as metal sources, borohydride as reducing agent and Carbon Vulcan XC72 as support. The synthetized PtRuIn/C electrocatalysts were characterized by X-ray diffraction (XRD), energy dispersive analysis (EDX), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperommetry (CA) and polarization curves in alkaline and acidic electrolytes (single cell experiments). The XRD patterns show Pt peaks are attributed to the face-centered cubic (fcc) structure, and a shift of Pt (fcc) peaks indicates that Ru or In is incorporated into Pt lattice. TEM micrographs show metal nanoparticles with an average nanoparticle size between 2.7 and 3.5 nm. Methanol oxidation in acidic and alkaline electrolytes was investigated at room temperature, by CV and CA. PtRu/C (50:50) shows the highest activity among all electrocatalysts in study considering methanol oxidation for acidic and alkaline electrolyte. Polarization curves at 80°C show PtRuIn/C (50:25:25) with superior performance for methanol oxidation, when compared to Pt/C, PtIn/C and PtRu/C for both electrolytes. The best performance obtained by PtRuIn/C (50:25:25) in real conditions could be associated with the increased kinetics reaction and/or with the occurrence simultaneously of the bifunctional mechanism and electronic effect resulting from the presence of Pt alloy.