Influence of dopant, pH and potential on the spectral changes of poly(o-methoxyaniline): relationship with the redox processes

Gazotti, W.A.; Jannini, Marcelo J. D. M.; Torresi, Susana Inês Córdoba de; Paoli, Marco

doi:10.1016/s0022-0728(97)80056-3

Cited by 25 publications

(26 citation statements)

References 26 publications

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“…Both electrochromism and electroactivity are related to the injection/ejection of charge carriers into/from the polymeric matrix. On this basis, we can associate the absorbance (A) with the inserted charge per unit area, as it was already done for inorganic and organic materials 11,12 :…”

Section: Methodsmentioning

confidence: 99%

“…This analysis is specially useful in the case of poly(2-ethylaniline) which shows very complicated i/E profiles. This method has already been applied for nickel hydroxide 11 and poly(o-metoxyaniline) 12 and it is based on the fact that changes in absorbance during electrochemical processes are proportional to the electric charge consumed in those processes when the differential absorption curves coincide with the voltammetric profiles. In this way, both curves must coincide at the wavelengths in which the species taking part in the electrochemical reaction absorb light.…”

Section: Introductionmentioning

confidence: 99%

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Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Schemid

Torresi

Bassetto

et al. 2000

J. Braz. Chem. Soc.

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Neste trabalho foi feito um estudo comparativo da estrutura, morfologia e resposta espectroeletroquímica da poli (2-etilanilina) e da polianilina em função do contra-íon. Os ácidos minerais conferem uma estrutura mais esponjosa a filmes de poli (2-etilanilina) enquanto que ácidos orgânicos tornam a estrutura homogênea e compacta. Para a poli (2-etilanilina) a resposta eletroquímica depende muito da relação carga/tamanho do eletrólito utilizado, devido a efeitos estéricos e eletrônicos. As relações entre as bandas de absorção e os pares redox mostram que mudanças na absorbância são proporcionais a corrente faradaica que é observada nos voltamogramas.In this paper a comparative study of the structure, morphology, and the spectroelectrochemical response of poly (2-ethyl aniline) and polyaniline for different counterions is presented. Spongeous structure of poly (2-ethyl aniline) is obtained when mineral acids are used, while homogeneous and compact films are formed using organic acids. The electrochemical response of poly (2-ethyl aniline) depends on the charge/size ratio of the counterion due to both steric and electronic effects. The correlation between the absorption bands and the redox couple show that the changes in absorbance are proportional to the faradaic current observed in the voltammograms.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Schemid

Torresi

Bassetto

et al. 2000

J. Braz. Chem. Soc.

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“…If the molar extinction coefficients are known at each wavelength, the current associated to each one of these processes could be estimated from Beer-Lambert and Faraday's laws. 45,46 If…”

Section: ͓2͔mentioning

confidence: 99%

“…However, the true coefficient should be larger than the highest value of the FdA/dQ function, because at each polarization potential, more than one electrochemical process that gives current change coexists and only one gives absorbance change. [45][46][47] Figure 3 shows the simulation of the cathodic voltammetric scan from dA/dt curves at 380 and 686 nm and Eq. 5c and ͉͑/SF͉͒ 686 = 200 C −1 .…”

Section: ͓2͔mentioning

confidence: 99%

Electronic Perspective on the Electrochemistry of Prussian Blue Films

Agrisuelas

Bueno

Ferreira

et al. 2009

J. Electrochem. Soc.

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The derivative of the voltabsommetric scans, together with previous nano-electrogravimetric and X-ray diffraction results, allow different electrochemical processes to be distinguished during the Prussian blue ͑PB͒ voltammetric scan. Potassium, proton, and hydrated proton counterions involved in PB electrochemistry are related here to the electrochemical reactions of specific Fe sites. Potassium counterions show two different sites for their insertion: one located in the crystalline framework and another in ferrocyanide vacancies. From the monitoring of electroactive Fe sites, the covalent-exchange model is suggested as one of the first approaches to explain the origin of the PB magnetic ordering observed at room temperature during voltammetric scanning. Systems that undergo reversible and controlled changes of their properties offer appealing perspectives for the fabrication of electronic switch devices. Thus, Prussian blue ͑PB͒-like materials have raised intense interest because of their electrochromic, ionexchange, ion-sensing, electrocatalytic, or photomagnetic properties, 1-5 because the PB Everitt's salt ͑ES͒ voltammetric scan is accompanied by reversible changes in these physicochemical properties.6-10 Likewise, they also display a wide range of important magnetic ͑e.g., room temperature magnetic ordering͒ and magnetooptical ͑e.g., ferromagnetism, photoinduced ͑de͒-magnetization͒ properties. [11][12][13][14] In particular, the PB electromagnetic properties can also be tailored by external conditions, such as the magnetic field, 15-17 light, 15,18,19 and by electrochemical methods. 18,[20][21][22][23][24] X-ray studies showed that the PB three-dimensional ͑3D͒ structure is face-centered cubic 25 with a general formula equal to Fe 4 ͓Fe͑CN͒ 6 ͔ 3 ·mH 2 O. Trivalent and divalent iron ions are in highand low-spin sites, Fe͑III͒ high-spin and Fe͑II͒ low-spin , respectively. 26Enclosed in this structure, high-and low-spin sites are both octahedral and surrounded by -NC and -CN units, respectively. Thus, the PB lattice is composed of repetitive units of Fe low-spin -CN-Fe high-spin in the three spatial directions. Nonetheless, 1 4 of low-spin Fe͑II͒ sites are missing and occupied by water molecules coordinated to Fe͑III͒ high-spin ions. The PB structure is completed with water molecules occupying interstitial positions. 27-29The above crystalline structure corresponds to the freshly deposited PB film following the electrochemical methodology described by Itaya et al. 22 and it is known as insoluble. The insoluble PB is electrochemically converted into the soluble PB by means of successive voltammetric cycles between the PB and ES forms 30,31 until a stable electrochemical response is achieved. 32 The soluble PB has been described as similar to the insoluble PB 3D structure. 33,34 Repetitive structural units of Fe low-spin -CN-Fe high-spin also compose its rigid framework, where 1 4 of the low-spin sites are missing. The position of the trivalent iron ions can be drawn as Fe͑II͒ low-spin -CN-Fe͑III͒ high-spin a...

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“…Ao lado das tradicionais polianilinas sulfonadas como SPAN e PAPSAH outras, utilizando grupos como metóxi e etóxi [115][116][117] , ácido benzoilsulfônico (PABSAH) 118 , ácido propil-benzenossulfônico (PAPBSAH) 119 131 .…”

Section: Figura 1 Variação Do Potencial Em Função Da Intercalação Deunclassified

Materiais para cátodos de baterias secundárias de lítio

Varela¹,

Huguenin²,

Malta³

et al. 2002

Quím. Nova

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Recebido em 21/12/00; aceito em 4/7/01 MATERIALS FOR CATHODES OF SECONDARY LITHIUM BATTERIES. In this work, cathodes employed in secondary lithium batteries are reviewed. These cathodes have great technologic and scientific importance, specifically, materials for cathodes as electronic conductor polymers (ECP), transition metal oxides (TMO) and nanocomposites of ECP/TMO. The use of a specific cathodic material is based in some intrinsic characteristics that improve the performance of the battery. Thus, some vantages and disvantages of these insertion compounds are discussed, as lithium insertion capacity, energy density, and the ciclability of these materials.Keywords: secondary lithium batteries; cathodic materials; transition metal oxides; electronic conducting polymers; nanocomposites. INTRODUÇÃOUma fonte eletroquímica de potência ou bateria pode ser definida como um dispositivo capaz de converter diretamente a energia liberada numa reação química em energia elétrica. As baterias apresentam basicamente duas funções principais, a primeira é agir como fontes portáteis de potência elétrica. A segunda, que tem crescido em importância nos últimos trinta anos, está baseada na habilidade de certos sistemas eletroquímicos de armazenar a energia suprida por uma fonte externa. Tais baterias são utilizadas, em veículos elé-tricos, fontes de emergência, como parte de um sistema de fornecimento de curta duração para demandas em pico e em conjunção com fontes renováveis de energia, como solar ou eólica, por exemplo.A primeira descrição de uma bateria eletroquímica foi feita pelo italiano Alessandro Volta em 1800. Tal "descoberta" representa o marco na história da eletroquímica e, particularmente, na história dos dispositivos denominados genericamente baterias. Desde então, um notável progresso tem sido feito na área de armazenamento eletroquímico de energia. Hoje, pode-se enumerar uma grande variedade de dispositivos englobados na categoria de baterias: células metal-ar, metal-hidreto metálico (Ni-HM), níquel-cádmio (Ni-Cd), células térmicas, íons-Lítio, entre outras.O mercado para dispositivos primários consiste basicamente na produção de baterias para aparelhos portáteis. As baterias secundá-rias ou recarregáveis representam maior interesse devido à grande demanda atual de aparelhos celulares e microcomputadores portá-teis. Em 1997, por exemplo, dos 34 bilhões de dólares movimentados com baterias, 24 foram destinados às baterias secundárias 1 .Graças à simplicidade e reversibilidade das reações eletroquímicas de inserção ou intercalação, a grande maioria dos dispositivos secundários que operam à temperatura ambiente é baseada nos chamados eletrodos de inserção. Como exemplos, têm-se os dispositivos secundários aquosos, como hidreto metálico/NiOOH ou Zn/MnO 2 , que envolvem a inserção de H + no hidreto metálico 2,3 ou MnO 2 4,5. Até mesmo o mecanismo de redução do eletrodo positivo das baterias de chumbo ácido, PbO 2 6,7 pode ser atribuído ao processo de inserção de H + 8 .Considerando-se a utilização de cátions metálicos...

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Influence of dopant, pH and potential on the spectral changes of poly(o-methoxyaniline): relationship with the redox processes

Cited by 25 publications

References 26 publications

Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Structural, morphological and spectroelectrochemical characterization of poly (2-ethyl aniline)

Electronic Perspective on the Electrochemistry of Prussian Blue Films

Materiais para cátodos de baterias secundárias de lítio

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