Sirlane Silva - Academia.edu (original) (raw)

Papers by Sirlane Silva

Research paper thumbnail of Estudo da oxidação eletroquímica do etanol em meio alcalino utilizando eletrocatalisadores PtAuIr/C e PdAuIr/C preparados via redução por borohidreto de sódio

in different atomic proportions, with 20 wt.% of metal loading and supported on Vulcan XC72 carbo... more in different atomic proportions, with 20 wt.% of metal loading and supported on Vulcan XC72 carbon with high surface area. The materials were characterized by X-ray dispersive energy spectroscopy (EDX), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The ethanol electrochemical oxidation was studied by cyclic voltammetry (CV), chronoamperometry and in situ using Fourier Transform Infrared Spectroscopy (FTIR) using the thin porous coating technique, Afterwards the materials were tested on direct ethanol alkaline fuel cells. The results suggest alloys formation, with the mean nanoparticles sizes are from 4-10 nm. According to the electrochemical experiments the ternary electrocatalysts presented higher electrocatalytic activity, while that the FTIR studies indicated that the main product of the electrochemical oxidation of ethanol in alkaline medium for all synthesized electrocatalysts was acetate, also suggesting that the oxidation occurs incompletely by the indirect mechanism. The fuel cell experiments showed the best results for PdAuIr/C (50:40:10), where these materials had an open circuit potential of approximately 0,78 V and maximum power density of about 15 mW cm-2 , about 333% higher than Pd/C.

Research paper thumbnail of Direct ammonia fuel cell performance using PtIr/C as anode electrocatalysts

International Journal of Hydrogen Energy, 2014

Direct ammonia fuel cell (DAFC) performance was investigated using as anode PtIr/C electrocatalys... more Direct ammonia fuel cell (DAFC) performance was investigated using as anode PtIr/C electrocatalysts (Pt:Ir atomic ratios of 50:50, 70:30, 80:20 and 90:10) prepared by the borohydride reduction process and NH 4 OH 1.0, 3.0 and 5.0 mol L À1 in KOH 1.0 mol L À1 as fuel. Xray analyses of PtIr/C electrocatalysts suggested the formation of PtIr alloy and the transmission electron micrographs showed the average particle diameters between 4.5 and 6.0 nm. Using PtIr/C 50:50 electrocatalyst and NH 4 OH 5.0 mol L À1 in KOH 1.0 mol L À1 at 40 C a maximum power density was 48% and 70% higher than that obtained using Pt/C and Ir/C electrocatalysts, respectively. The increase of electroactivity using PtIr/C electrocatalysts might be related to a decrease of poisoning on catalyst surface by N ads species and to an improved kinetic for ammonia oxidation reaction.

Research paper thumbnail of Para citações

Research paper thumbnail of PdBi/C electrocatalysts for ethanol electro-oxidation in alkaline medium

International Journal of Hydrogen Energy, 2011

borohydride reduction using Pd(NO 3) 2 .2H 2 O and Bi(NO 3) 3 .5H 2 O as metal sources and Vulcan... more borohydride reduction using Pd(NO 3) 2 .2H 2 O and Bi(NO 3) 3 .5H 2 O as metal sources and Vulcan XC72 as support. The electrocatalysts were characterized by energy-dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy and cyclic voltammetry. The activity for the ethanol electro-oxidation in alkaline medium was investigated at room

Research paper thumbnail of Electrochemical and Fuel Cell Evaluation of PtIr/C Electrocatalysts for Ethanol Electrooxidation in Alkaline Medium

Electrocatalysis, 2014

PtIr/C electrocatalysts prepared by borohydride reduction process were characterized by X-ray dif... more PtIr/C electrocatalysts prepared by borohydride reduction process were characterized by X-ray diffraction, transmission electron microscopy, and cyclic voltammetry. The X-ray diffraction measurements suggested the PtIr alloy formation; furthermore, peaks of IrO 2 were not observed; nevertheless, the presence of Ir oxides in small amounts and amorphous forms cannot be discarded. The transmission electron microscopy showed the average particle diameter between 4.0 and 6.0 nm for all compositions prepared. The catalytic activity for ethanol electrooxidation in alkaline medium at room temperature (cyclic voltammetry and chronoamperometry results) showed that PtIr/C (70:30) and PtIr (90:10) exhibited higher performance toward ethanol oxidation than the other electrocatalysts. Experiments using direct ethanol alkaline fuel cell at 75°C showed PtIr (90:10) as the best electrocatalyst and Ir/C as virtually inactive for ethanol oxidation in real conditions. The best result obtained using PtIr/C may be associated to the electronic effect between Pt and Ir that could decrease the poisoning on catalyst surface and also by the occurrence of bifunctional mechanism.

Research paper thumbnail of In Situ ATR-FTIR Studies of Ethanol Electro-oxidation in Alkaline Medium on PtRh/C Electrocatalyst Prepared by an Alcohol Reduction Process

Electrocatalysis, 2016

Anion exchange membrane fuel cell is a new chance to produce a functional and portable fuel cell;... more Anion exchange membrane fuel cell is a new chance to produce a functional and portable fuel cell; however, the studies are still at an early stage with few reports regarding the AEMFC. PtRh/C electrocatalysts with different Pt:Rh atomic ratios were prepared by an alcohol reduction process. X-ray diffraction patterns for all PtRh/C materials indicated no shift in Pt(fcc) peaks showing that Rh did not incorporated into Pt lattice; however, the analysis of lattice parameter showed that some Pt atoms are added to Rh(fcc) structure. The mean particle sizes were in the range of 4-5 nm. Electrochemical experiments showed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 had superior performance exhibiting a current density of 5.0 mA mg metal −1. From in situ ATR-FTIR experiments, it was observed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 produced more acetate ions than other ones, while the material prepared with Pt:Rh atomic ratio of 50:50 was more selective to CO 2 as observed in acid media.

Research paper thumbnail of Contribuições Da Educação Somática Para Os Profissionais Da Área Da Saúde Hospitalar

Revista Conexao UEPG, 2016

RESUMO O projeto extensionista "Práticas somáticas aplicadas aos funcionários e servidores do Hos... more RESUMO O projeto extensionista "Práticas somáticas aplicadas aos funcionários e servidores do Hospital São João Batista-Fundação Assistencial Viçosense", vinculado ao programa PIBEX, teve como objetivo principal pesquisar e analisar as contribuições das práticas somáticas no tratamento e prevenção das disfunções psicossomáticas dos funcionários e servidores deste hospital, que se localiza no município de Viçosa-MG. Participaram deste estudo 115 funcionários, divididos em diversos setores do hospital. Para a coleta de dados, foram utilizados questionário diagnóstico inicial, diário de bordo e entrevista focal. Por meio das anotações no diário de bordo e resultados das entrevistas focais, percebemos que as sessões práticas proporcionaram aos participantes bem-estar físico e mental, bem como contribuíram para amenizar ou sanar tensões e estresses relacionados a jornadas ininterruptas de trabalho. Concluímos que as práticas somáticas podem trazer bem-estar integral aos indivíduos, no sentido de que equilibram as funções corpo e mente. Palavras chave: Educação somática. Disfunções psicossomáticas. Lian Gong.

Research paper thumbnail of PdAu/C Electrocatalysts as Anodes for Direct Formate Fuel Cell

Electrocatalysis, 2015

ABSTRACT PdAu/C electrocatalysts in different atomic ratios (90:10, 80:20, 70:30, and 50:50) supp... more ABSTRACT PdAu/C electrocatalysts in different atomic ratios (90:10, 80:20, 70:30, and 50:50) supported on Vulcan XC72 carbon were evaluated toward formate oxidation in alkaline media. The materials were prepared by the borohydride process. X-ray diffraction (XRD) patterns of PdAu materials showed peak characteristic of Pd and Au face-centered-cubic (fcc) structures while transmission electron micrographs (TEM) showed the nanoparticles with particle size between 4 and 10 nm for all electrocatalysts. Experiments considering single cell suggested the PdAu/C (90:10) and PdAu/C (80:20) as promisors for formate oxidation. The best result obtained was attributed to the presence of Au in small quantities that contributes to the formate adsorption.

Research paper thumbnail of Estudo do efeito do suporte em catalisadores de Cobalto e Níquel para obtenção de Hidrogênio a partir da reforma a vapor do etanol

Research paper thumbnail of Estudo da oxidação eletroquímica do etanol em meio alcalino utilizando eletrocatalisadores PtAuIr/C e PdAuIr/C preparados via redução por borohidreto de sódio

in different atomic proportions, with 20 wt.% of metal loading and supported on Vulcan XC72 carbo... more in different atomic proportions, with 20 wt.% of metal loading and supported on Vulcan XC72 carbon with high surface area. The materials were characterized by X-ray dispersive energy spectroscopy (EDX), X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The ethanol electrochemical oxidation was studied by cyclic voltammetry (CV), chronoamperometry and in situ using Fourier Transform Infrared Spectroscopy (FTIR) using the thin porous coating technique, Afterwards the materials were tested on direct ethanol alkaline fuel cells. The results suggest alloys formation, with the mean nanoparticles sizes are from 4-10 nm. According to the electrochemical experiments the ternary electrocatalysts presented higher electrocatalytic activity, while that the FTIR studies indicated that the main product of the electrochemical oxidation of ethanol in alkaline medium for all synthesized electrocatalysts was acetate, also suggesting that the oxidation occurs incompletely by the indirect mechanism. The fuel cell experiments showed the best results for PdAuIr/C (50:40:10), where these materials had an open circuit potential of approximately 0,78 V and maximum power density of about 15 mW cm-2 , about 333% higher than Pd/C.

Research paper thumbnail of Direct ammonia fuel cell performance using PtIr/C as anode electrocatalysts

International Journal of Hydrogen Energy, 2014

Direct ammonia fuel cell (DAFC) performance was investigated using as anode PtIr/C electrocatalys... more Direct ammonia fuel cell (DAFC) performance was investigated using as anode PtIr/C electrocatalysts (Pt:Ir atomic ratios of 50:50, 70:30, 80:20 and 90:10) prepared by the borohydride reduction process and NH 4 OH 1.0, 3.0 and 5.0 mol L À1 in KOH 1.0 mol L À1 as fuel. Xray analyses of PtIr/C electrocatalysts suggested the formation of PtIr alloy and the transmission electron micrographs showed the average particle diameters between 4.5 and 6.0 nm. Using PtIr/C 50:50 electrocatalyst and NH 4 OH 5.0 mol L À1 in KOH 1.0 mol L À1 at 40 C a maximum power density was 48% and 70% higher than that obtained using Pt/C and Ir/C electrocatalysts, respectively. The increase of electroactivity using PtIr/C electrocatalysts might be related to a decrease of poisoning on catalyst surface by N ads species and to an improved kinetic for ammonia oxidation reaction.

Research paper thumbnail of Para citações

Research paper thumbnail of PdBi/C electrocatalysts for ethanol electro-oxidation in alkaline medium

International Journal of Hydrogen Energy, 2011

borohydride reduction using Pd(NO 3) 2 .2H 2 O and Bi(NO 3) 3 .5H 2 O as metal sources and Vulcan... more borohydride reduction using Pd(NO 3) 2 .2H 2 O and Bi(NO 3) 3 .5H 2 O as metal sources and Vulcan XC72 as support. The electrocatalysts were characterized by energy-dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy and cyclic voltammetry. The activity for the ethanol electro-oxidation in alkaline medium was investigated at room

Research paper thumbnail of Electrochemical and Fuel Cell Evaluation of PtIr/C Electrocatalysts for Ethanol Electrooxidation in Alkaline Medium

Electrocatalysis, 2014

PtIr/C electrocatalysts prepared by borohydride reduction process were characterized by X-ray dif... more PtIr/C electrocatalysts prepared by borohydride reduction process were characterized by X-ray diffraction, transmission electron microscopy, and cyclic voltammetry. The X-ray diffraction measurements suggested the PtIr alloy formation; furthermore, peaks of IrO 2 were not observed; nevertheless, the presence of Ir oxides in small amounts and amorphous forms cannot be discarded. The transmission electron microscopy showed the average particle diameter between 4.0 and 6.0 nm for all compositions prepared. The catalytic activity for ethanol electrooxidation in alkaline medium at room temperature (cyclic voltammetry and chronoamperometry results) showed that PtIr/C (70:30) and PtIr (90:10) exhibited higher performance toward ethanol oxidation than the other electrocatalysts. Experiments using direct ethanol alkaline fuel cell at 75°C showed PtIr (90:10) as the best electrocatalyst and Ir/C as virtually inactive for ethanol oxidation in real conditions. The best result obtained using PtIr/C may be associated to the electronic effect between Pt and Ir that could decrease the poisoning on catalyst surface and also by the occurrence of bifunctional mechanism.

Research paper thumbnail of In Situ ATR-FTIR Studies of Ethanol Electro-oxidation in Alkaline Medium on PtRh/C Electrocatalyst Prepared by an Alcohol Reduction Process

Electrocatalysis, 2016

Anion exchange membrane fuel cell is a new chance to produce a functional and portable fuel cell;... more Anion exchange membrane fuel cell is a new chance to produce a functional and portable fuel cell; however, the studies are still at an early stage with few reports regarding the AEMFC. PtRh/C electrocatalysts with different Pt:Rh atomic ratios were prepared by an alcohol reduction process. X-ray diffraction patterns for all PtRh/C materials indicated no shift in Pt(fcc) peaks showing that Rh did not incorporated into Pt lattice; however, the analysis of lattice parameter showed that some Pt atoms are added to Rh(fcc) structure. The mean particle sizes were in the range of 4-5 nm. Electrochemical experiments showed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 had superior performance exhibiting a current density of 5.0 mA mg metal −1. From in situ ATR-FTIR experiments, it was observed that PtRh/C electrocatalyst with Pt:Rh atomic ratio of 70:30 produced more acetate ions than other ones, while the material prepared with Pt:Rh atomic ratio of 50:50 was more selective to CO 2 as observed in acid media.

Research paper thumbnail of Contribuições Da Educação Somática Para Os Profissionais Da Área Da Saúde Hospitalar

Revista Conexao UEPG, 2016

RESUMO O projeto extensionista "Práticas somáticas aplicadas aos funcionários e servidores do Hos... more RESUMO O projeto extensionista "Práticas somáticas aplicadas aos funcionários e servidores do Hospital São João Batista-Fundação Assistencial Viçosense", vinculado ao programa PIBEX, teve como objetivo principal pesquisar e analisar as contribuições das práticas somáticas no tratamento e prevenção das disfunções psicossomáticas dos funcionários e servidores deste hospital, que se localiza no município de Viçosa-MG. Participaram deste estudo 115 funcionários, divididos em diversos setores do hospital. Para a coleta de dados, foram utilizados questionário diagnóstico inicial, diário de bordo e entrevista focal. Por meio das anotações no diário de bordo e resultados das entrevistas focais, percebemos que as sessões práticas proporcionaram aos participantes bem-estar físico e mental, bem como contribuíram para amenizar ou sanar tensões e estresses relacionados a jornadas ininterruptas de trabalho. Concluímos que as práticas somáticas podem trazer bem-estar integral aos indivíduos, no sentido de que equilibram as funções corpo e mente. Palavras chave: Educação somática. Disfunções psicossomáticas. Lian Gong.

Research paper thumbnail of PdAu/C Electrocatalysts as Anodes for Direct Formate Fuel Cell

Electrocatalysis, 2015

ABSTRACT PdAu/C electrocatalysts in different atomic ratios (90:10, 80:20, 70:30, and 50:50) supp... more ABSTRACT PdAu/C electrocatalysts in different atomic ratios (90:10, 80:20, 70:30, and 50:50) supported on Vulcan XC72 carbon were evaluated toward formate oxidation in alkaline media. The materials were prepared by the borohydride process. X-ray diffraction (XRD) patterns of PdAu materials showed peak characteristic of Pd and Au face-centered-cubic (fcc) structures while transmission electron micrographs (TEM) showed the nanoparticles with particle size between 4 and 10 nm for all electrocatalysts. Experiments considering single cell suggested the PdAu/C (90:10) and PdAu/C (80:20) as promisors for formate oxidation. The best result obtained was attributed to the presence of Au in small quantities that contributes to the formate adsorption.

Research paper thumbnail of Estudo do efeito do suporte em catalisadores de Cobalto e Níquel para obtenção de Hidrogênio a partir da reforma a vapor do etanol