SOLANGE KAZUMI SAKATA

SOLANGE KAZUMI SAKATA

(Fonte: Lattes)

Resumo

Possui graduação em Química bacharelado e licenciatura pela Universidade de São Paulo. Doutorado na área de Química Orgânica, com ênfase em Eletrossintese Orgânica pelo Instituto de Química da Universidade de São Paulo. Pós - doutorados em Biotecnologia no Scripps Institution of Oceanography na University of California - San Diego -USA) e no Instituto de Química da Universidade de São Paulo. Foi pesquisadora visitante no Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB-Stuttgart - Alemanha no estudo do metagenoma na produção de enzimas para fins catalíticos e no Centro Tecnológico da Marinha de São Paulo (CTM-SP) no desenvolvimento e caracterização de polímeros. Atualmente é pesquisadora do Instituto de Pesquisas Energéticas e Nucleares (IPEN- SP / CNEN) no Centro de Tecnologia das Radiações e estuda o efeitos das radiações em nano materiais de carbono. (Texto extraído do Currículo Lattes em 27 dez. 2021).

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Characteristics of electric double layer capacitors prepared with electrolytes based on deep eutectic solvents
2022 - GALDINO, G.S.; RODRIGUES, W.C.; CRUZ, P.D.; CASINI, J.S.; SAKATA, S.K.; FARIA, R.N.
The storage capacity of electric double layer capacitors or electrochemical supercapacitors with electrolytes based on deep eutectic solvents (DES) composed of L-lactic acid with several hydrogen bond acceptors (nicotinamide, L-alanine, ammonium acetate, sodium acetate, choline chloride, amino acetic acid) with a molar ratio of 7:1 have been investigated. A DES based on urea and choline chloride with at a molar ration of 2:1 has also been included for comparison. The electrochemical supercapacitors were prepared using commercial activated carbon electrodes after removing the volatile organic electrolyte with a vacuum pump. The characteristics of the electrochemical supercapacitors were determined by cyclic voltammetry at temperature room temperature and also after heating at 353 K using scan rates that varied from 2 to 25 mVs-1. Lowest scan rate led to higher specific capacitance of 150±8 Fg-1 with a maximum applied potential of 1.7 V for the urea and choline chloride DES with a molar ration of 2:1. The lactic acid with all the hydrogen bond acceptors with a molar ratio 7:1 it has been necessary to increase the temperature above room temperature to improve the specific capacitance.
Characteristics of electric double layer capacitors produced with electrolytes based on deep eutectic solvents
2022 - GALDINO, G.S.; RODRIGUES, W.C.; CRUZ, P.D.; CASINI, J.S.; SAKATA, S.K.; FARIA, R.N.
The storage capacity of electric double layer capacitors or supercapacitors with electrolytes based on deep eutectic solvents (DES) has been investigated in this study. DES composed of L-lactic acid with nicotinamide, L-alanine, ammonium acetate, sodium acetate and choline chloride have all been prepared at a molar ratio of 7:1. Furthermore, urea with choline chloride at a molar ratio of 2:1 has also been used as electrolyte for the electrochemical supercapacitors. The DES supercapacitors were prepared using commercial activated carbon electrodes after removing the volatile organic electrolyte with back-pumping vacuum. The electric characteristics of these supercapacitors with DES electrolytes were determined by cyclic voltammetry at room temperature and above up to 80°C. The cyclic voltammetry scan rates were varied from 2 to 25 mVs-1. The lowest scan rate led to a high specific capacitance of 150±8 Fg-1 for urea with choline chloride at a molar ratio of 2:1 and using a maximum applied potential of 1.7 V. For higher molar ratio (7:1) of Llactic acid with the others hydrogen bond acceptors (HBA) it was necessary to increase the temperature above room temperature to improve the specific capacitance. The best results have been obtained with two solids (urea and choline chloride) as starting compounds for preparing the DES. Equivalent series resistances (ESR) have also been determined in this work employing galvanostatic cycling tests with current densities between 2 and 20 mAg-1.
Low-temperature reduction of graphene oxide using the HDDR process for electrochemical supercapacitor applications
2020 - BENITEZ JARA, F.G.; CRUZ, P.D.V.; BARBOSA, L.P.; CASINI, J.C.S.; SAKATA, S.K.; PERUZZI, A.J.; FARIA, R.N.
In the present work, attempts of reducing a graphene oxide powder using a low temperature hydrogenation disproportionation desorption and the recombination process (L-HDDR) has been carried out. A lower processing temperature in large scale production is significant when costs are concerned. Graphite oxide was prepared using a modified Hummers’ method dispersed in ethanol and exfoliated using ultrasonication to produce Graphene Oxide (GO). Investigations have been carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results of L-HDDR processing graphene oxide powder, using unmixed hydrogen at 400°C and relatively low pressures (<2 bars) have been reported. X-ray diffraction patterns showed a reduction of graphene oxide with the L-HDDR process. The results showed that both processes, the L-HDDR as well as the standard HDDR, may be applied to the reduction of graphene oxide in order to produce supercapacitor materials. The advantage of employing the L-HDDR process is a relatively low temperature reducing the cost of treatment, what is a very important factor for producing a large amount of material. Thus, the L-HDDR process has been considered a promising alternative method of reducing graphene oxide with efficiency, with the possibility of large scale production.
Microstructural and electrochemical studies of HDDR-graphene supercapacitors electrodes in KOH electrolyte
2018 - GALDINO, G.S.; SILVA, D.V.; CRUZ, P.D.; CASINI, J.S.; SAKATA, S.K.; FARIA, R.N.
In the past, the hydrogenation disproportionation desorption and recombination (HDDR) process has only been used to produced rare earth transition metal polymer bonded permanent magnets with outstanding performance. Recently, however, it has been shown that the HDDR process (850oC) can be successfully employed to produce reduced graphene oxide for electrochemical supercapacitors. In the present work, the electrochemical characteristics of HDDR-graphene supercapacitors have been compared to those obtained with chemically reduced commercial graphene oxide. Lower HDDR processing temperatures (200-600oC) have been used in this study for a comparison with previous investigations. The equivalent series and parallel resistances (EPR and ESR) and specific capacitance (Cs) of HDDR-graphene supercapacitors electrodes have been investigated using cyclic voltammetry. Room temperature specific capacitances calculated from cyclic voltammetry curves at scan rates of 2 mVs-1 reached ~160 Fg-1 in 1 molL-1 KOH electrolyte. Internal series resistances of the HDDR-graphene electrodes were measured using the galvanostatic curves also at room temperature. The microstructures of the electrode material have been investigated using scanning electron microscopy (SEM) and chemical microanalyses employing energy dispersive X-ray analysis (EDX).
Low-temperature reduction of graphene oxide using the HDDR process for electrochemical supercapacitor applications
2018 - BENITEZ JARA, F.G.; CRUZ, P.V.; BARBOSA, L.P.; CASINI, J.C.S.; PERUZZI, A.J.; SAKATA, S.K.; FARIA, R.N.
In the present work, attempts of reducing a graphene oxide powder using a low temperature hydrogenation disproportionation desorption and recombination process (L-HDDR) has been carried out. A lower processing temperature in large scale production is significant as far as costs are concerned. Graphite oxide was prepared using a modified Hummers’ method and dispersed in ethanol, exfoliated using ultrasonication to produce Graphene Oxide (GO). Investigations have been carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results of L-HDDR processing graphene oxide powder using unmixed hydrogen at 400°C and relatively low pressures (<2 bars) have been reported. X-ray diffraction patterns showed a reduction of graphene oxide with the L-HDDR process. The results showed that the L-HDDR process, as the standard HDDR process, can be applied to the reduction of graphene oxide to produce supercapacitor materials. The advantage of employing the L-HDDR process is a relatively a low temperature would reduce the cost of treatment that is a very important factor for producing large amount of material. Thus, the L-HDDR process has been considered a promising alternative method of reducing graphene oxide with efficiency and possibly in large scale production.
Electron beam irradiation of reduced graphene oxide-palladium nanocomposite for electrochemical supercapacitor
2017 - GALDINO, GABRIEL S.; FERREIRA SOBRINHO, LUIZA; CRUZ, PEDRO V.D.; CASINI, JULIO C.S.; SAKATA, SOLANGE K.; FARIA JUNIOR, RUBENS N.
Recent work has shown that palladium nanoparticle–graphene composite can be an efficient electrode material in energy storage applications in supercapacitors. These Pd-based supercapacitors showed remarkable properties with a maximum specific capacitance of 637 F g -1 and also exhibited excellent cycle life with 91.4% of the initial specific capacitance retained after 10000 cycles. Palladium nanoparticle decorated graphene composite was synthesized via a chemical approach in a single step by the simultaneous reduction of graphene oxide and palladium chloride from the aqueous phase using ascorbic acid as reducing agent. In the present work, electron beam irradiation has been investigated as an attempt to produce graphene-palladium nanocomposites. Graphite oxide was prepared using a modified Hummers’ method and dispersed in ethanol, exfoliated using ultrasonication to produce Graphene Oxide (GO) and dried for further analysis and processing. This material was thermic reduced in high vacuum (10 -6 mbar) at various temperatures (200-600 o C) and mixed in a solution with palladium. The samples were placed in a 50 ml beaker with Pd(NO 2 ) 2 2H 2 O and were irradiated with 300kGy , dose rate 1,6 kGy s -1 . Irradiation was carried out in an electron accelerator Dynamitron de 37,5 kW (E = 1,5 MeV, 25 mA) (Radiation Dynamics Inc.), The resulting irradiated material was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These investigations showed that a palladium graphene mixture for supercapacitors applications is formed by electron beam irradiation.