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Study of copper electrodeposition mechanism from a strike alkaline bath prepared with 1-hydroxyethane-1,1-diphosphonic acid through cyclic voltammetry technique

PECEQUILO, Cristiane Vargas; PANOSSIAN, Zehbour
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
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Copper strike baths are extensively used in metal plating industry as they present the ability to plate adherent copper layers on less-noble metal substrates such as steel and zinc die castings. However, in the last few years, due to environmental controls and safety policies for operators, the plating industry has been interested in replacing the toxic cyanide copper strike baths with environmentally friendly baths. A broad bibliographic review showed that the published papers, referring to the new nontoxic copper strike baths, are patents, having little or no emphasis focused on electrodeposition mechanisms. Therefore, it was decided to study the copper electrodeposition mechanism from a strike alkaline bath prepared with one of the most nontoxic chelating agents cited in many patents which is the 1-hydroxyethane-1,1-diphosphonic acid, known as HEDP. This acid forms very stable water soluble complexes with Cu(2+) ions, thus cupric sulfate was used for preparing the plating bath. The results obtained through a cyclic voltammetry technique showed that Cu(2+) ion reduction to Cu from an HEDP electrodeposition bath occurs via a direct reduction reaction without a formation of Cu(+) intermediates. (C) 2010 Elsevier Ltd. All rights reserved.; Atotech of Brazil; Institute for Technological Research of Sao Paulo State...

KI effects on the reversible electrodeposition of silver on poly(ethylene oxide) for application in electrochromic devices

OLIVEIRA, M. R. S.; MELLO, D. A. A.; PONZIO, E. A.; OLIVEIRA, S. C. de
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
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A new approach to electrochromics, based on the reversible coating-dissolution of an oxide from an inorganic electrochromic electrolyte consisting of a silver-amine complex in a polymer electrolyte (PEO), has proven successful. The reversible electrodeposition of silver onto indium-tin oxide coated glass (ITO) was investigated and the influence of HClO(4) and KI was evaluated. Several characteristics of the electrolyte Ag-PEO make it suitable for use in electrochromic reversible silver electrodeposition devices, such as visible absorption spectrum with an absorbance variation of 60%, an electrochromic efficiency of 5.2 cm(2) C(-1) and an ionic conductivity 4.4 x 10(-4) S cm(-1). The addition of perchloric acid improved the transparency of Ag-PEO, and potassium iodide (KI) was fundamental in setting up the process of reversible silver electrodeposition in the PEO polymeric matrix. A description of the electrochemical processes implied is presented. A number of approaches focusing on the improvement of system performance are tested. (C) 2009 Elsevier Ltd. All rights reserved.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq; Fundacao de Amparo a Pesquisa do Estado do Rio de Janeiro-FAPERJ[E-26/110.173/2009]; Fundacao de Apoio ao Desenvolvimento do Ensino...

The processes involved in the Se electrodeposition and dissolution on Au electrode: the H2Se formation

SOLALIENDRES, M. O.; MANZOLI, A.; SALAZAR-BANDA, G. R.; EGUILUZ, K. I. B.; TANIMOTO, S. T.; MACHADO, S. A. S.
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
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The processes involved in the Se electrodeposition, mainly the one related to the formation of H2Se species on Au electrode in perchloric acid solutions, have been investigated through cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM), rotating ring-disc electrode (RRDE), and atomic force microscopy (AFM) techniques. In the experiments performed with the EQCM, with the potential sweep in the negative direction, the responses for the mass variation were divided in three well-defined potential regions: A (from 1.55 to 0.35 V), B (from 0.35 to -0.37 V), and C (from -0.37 to -0.49 V). It was verified that the following processes can occur, respectively: the species (AuO)(2)H2SeO3 was desorbed during the AuO reduction, the reduction of Se(IV) to Se(0), and the formation of H2Se. When the potential was swept in the positive direction, the responses for the mass variation were divided in four well-defined potential regions: D (from -0.49 to 0.66 V), E (from 0.66 to 0.99 V), F (from 0.99 to 1.26 V), and G (from 1.26 to 1.55 V), and the described processes in these regions were, respectively: the Se deposition and adsorption of water molecules and/or perchlorate ions, the Se dissolution, the Se incorporating mass in the form of HO-Se...

Electrodeposition of PVA-protected PtCo electrocatalysts for the oxygen reduction reaction in H2SO4

Gasparotto, Luiz Henrique da Silva; Ciapina, Eduardo Gonçalves; Ticianelli, Edson Antonio; Tremiliosi Filho, Germano
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
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In this paper we report the electrosynthesis of PVA-protected PtCo films (PVA = poly(vinylalcohol)) and their activities towards the oxygen reduction reaction (ORR). PtCo electrodeposits were potentiostatically obtained in the presence and absence of PVA at distinct potentials. The film morphology and composition were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), which revealed that the use of PVA in the electrodeposition of PtCo films was decisive to achieve better film composition control. Cyclic voltammetry for PVA-protected PtCo films showed that the electrochemical surface area is dependent on the electrodeposition potentials and suggested different adsorption strengths of oxygen-containing species. Films produced in the presence of PVA presented the following activity order towards ORR as a function of the electrodeposition potential (vs. Ag/AgCl): -0.9 V> -0.8 V> -1.0 V> -0.7 V. In contrast, PtCo films electrodeposited in the absence of PVA displayed very similar activities regardless of the electrodeposition potential. The simplicity of the electrodeposition method combined with its effectiveness enabled the production of "model electrodes" for investigating the fundamental aspects of the reactions taking place in the fuel cell cathodes. (C) 2011 Elsevier B.V. All rights reserved.; FAPESP; FAPESP; CNPq; CNPq; CAPES; CAPES

Solid electrolytes for electrochromic devices based on reversible metal electrodeposition

Mello, Dante A. A. de; Oliveira, Marcio R. S.; Oliveira, Lincoln C. S. de; Oliveira, Silvio C. de
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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Air conditioning and lighting costs can be reduced substantially by changing the optical properties of "intelligent windows." The electrochromic devices studied to date have used copper as an additive. Copper, used here as an electrochromic material, was dissolved in an aqueous animal protein-derived gel electrolyte. This combination constitutes the electrochromic system for reversible electrodeposition. Cyclic voltammetry, chronoamperometric and chromogenic analyses indicated that were obtained good conditions of transparency (initial transmittance of 70%), optical reversibility, small potential window (2.1 V), variation of transmittance in visible light (63.6%) and near infrared (20%) spectral regions. Permanence in the darkened state was achieved by maintaining a lower pulse potential (-0.16 V) than the deposition potential (-1.0 V). Increasing the number of deposition and dissolution cycles favored the transmittance and photoelectrochemical reversibility of the device. The conductivity of the electrolyte (10(-3) S/cm) at several concentrations of CuCl2 was determined by electrochemical impedance spectroscopy. A thermogravimetric analysis confirmed the good thermal stability of the electrolyte, since the mass loss detected up to 100 degrees C corresponded to water evaporation and decomposition of the gel started only at 200 degrees C. Micrographic and small angle X-ray scattering analyses indicated the formation of a persistent deposit of copper particles on the ITO. (C) 2012 Elsevier B.V. All rights reserved.; CAPES; FUNDECT [23/200.362/2008]; PROPP-UFMS; CNPq; FADEMS

Contribuições ao processo de eletrodeposição do gálio sobre cobre e estudo das interfases Cu/NaOH e Pt/NaOH na ausência e presença de íons acrilato; Contributions to the electrodeposition process of gallium on copper and study of the interphases Cu/NaOH and Pt/NaOH in the absence and in the presence of acrylate ions

Santos, Celia Aparecida Lino dos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/08/2003 PT
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Interfases Cu/NaOH e Pt/NaOH foram estudadas a 25 oC, a várias concentrações de NaOH, 1,0 x10-3 mol.L-1 a 5,0 mol.L-1, empregando técnicas eletroquímicas e não eletroquímicas na ausência e presença do íon acrilato. Os estudos tiveram como objetivo obter informações sobre a dupla camada elétrica (DCE) e sobre a reação H2O/H2 empregando cobre como substrato, para um melhor entendimento da eletrodeposição do gálio. Os estudos foram precedidos de ensaios tecnológicos em que as condições experimentais e a natureza dos sistemas a serem estudados foram estabelecidas. Estudos por voltametria cíclica provaram que em NaOH 5,0 mol.L-1 os processos de oxidação e redução do cobre são qualitativamente semelhantes aos observados em NaOH 0,1 mol.L-1, mas a velocidade destes processos se torna uma ordem de grandeza maior em NaOH 5,0 mol.L-1. Ensaios por voltametria linear indicaram que a redução dos óxidos na superfície e a menor pureza do cobre (99,99% comparado a 99,999 %) elevam a velocidade da reação H2O/H2. Estudos cronoamperométricos mostraram a viabilidade do emprego desta técnica nos estudos da DCE da interfase Cu/NaOH 5,0 mol.L-1 na região de potencial em que os processos faradaicos são da ordem de 20 microA.cm-2 em condições estacionárias. As interfases Cu/NaOH foram comparadas com as interfases Pt/NaOH e os resultados obtidos por cronoamperometria...

Aplicação de complexos de metais de transição coordenados a típicos aditivos orgânicos de banhos eletrolíticos em eletrodeposição binária de metais; Application of transition metal complexes coordinated with typical organic aditive from electrolitic bath for binary metal electrodeposition

Watanabe, Rogério Haruo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/07/2008 PT
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O objetivo principal deste trabalho é aplicar complexos de cobre(II), níquel(II), zinco(II) e nióbio(V) como fontes de metais em banhos de eletrodeposição. Os íons metálicos foram coordenados aos ligantes íon oxalato, íon citrato, etilenodiamina (EDA) ou tetraetilenopentamina (TEPA), os quais são aditivos orgânicos típicos em banhos de eletrodeposição. Os complexos foram caracterizados por análise elementar, espectroscopias nas regiões do infravermelho e ultravioleta-visível e voltametria cíclica. Foram realizadas eletrólises em presença de dois complexos de coordenação em ausência de quantias adicionais de aditivos, usando aço 1010 como substrato a pH = 4.5 (H2SO4/Na2SO4), resultando em depósitos com dois elementos metálicos. Os depósitos apresentaram aspectos morfológicos com boas qualidades e sem falhas. Em adição, os depósitos foram analisados por EDX, reflectância difusa e espectroscopia de raio-X e também foram realizadas medidas de curvas de polarização. Os depósitos obtidos a partir dos complexos gerados ex-situ mostraram morfologias melhores do que depósitos obtidos de soluções preparadas com os sais dos metais na presença dos aditivos, mediante as mesmas condições de trabalho. É sugerido que os metais de partida...

Eletrodeposição de filmes finos e materiais nanoestruturados das ligas magnéticas cobalto-níquel e cobalto-níquel-molibdênio; Electrodeposition of CoNi and CoNiMo magnetic alloys thin films and nanowires

Esteves, Marcos Cramer
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/05/2009 PT
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Este trabalho trata do estudo da eletrodeposição de filmes finos e nanofios magnéticos compostos de cobalto, níquel e molibdênio. Foi avaliada a influência da composição química das soluções utilizadas nas propriedades do material obtido. O uso de uma célula de Hull com eletrodo cilíndrico rotativo permitiu também que fosse estudado com mais detalhe o mecanismo de eletrodeposição da liga CoNiMo. Os filmes finos magnéticos de CoNi e CoNiMo foram eletrodepositados galvanostaticamente utilizando soluções contento citrato ou glicina como aditivo. Composição, microestrutura, morfologia e propriedades magnéticas dos depósitos foram analisados e a influência da composição das soluções e das densidades de corrente aplicadas foi avaliada. Soluções contendo citrato e/ou baixo pH não resultaram em filmes com boas propriedades. O uso de glicina e pH 7 resultou em filmes amorfos e com melhores propriedades magnéticas: magnetização de saturação de 1,2 T e coercividade de 50 Oe. Com o uso da célula de Hull rotativa foi possível avaliar como variava a composição da liga e as densidades de corrente parciais de cada um dos elementos. Notou-se que a deposição de Ni era menor quanto maior a concentração de Co+2 na solução e que o aumento na concentração de glicina favorece a deposição de Co e Mo e prejudica a deposição de Ni. Além disso...

Removal of Cd2+ ion from diluted aqueous solutions by electrodeposition on reticulated vitreous carbon electrodes

Tramontina, Jucelânia; Azambuja, Denise Schermann; Piatnicki, Clarisse Maria Sartori
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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A eletrodeposição do íon Cd2+ foi investigada em soluções aeradas de ácido sulfúrico-sulfato de potássio em pH 4,8. Sob condições potenciostáticas, usando eletrodos de carbono vítreo reticulado (CVR) de 30, 60 e 100 poros por polegada (ppp), uma elevada eficiência de remoção foi obtida para soluções contendo 5 e 10 mg L-1 de íon Cd2+, na faixa de potenciais entre –0,90 e –1,10 V. Neste intervalo, a eletrodeposição do cádmio é controlada por transporte de massa e a concentração de íon Cd+2 varia exponencialmente com o tempo, seguindo uma cinética de pseudo-primeira ordem. Para a concentração 10 mg L-1 de íon Cd2+ e usando o eletrodo de 30 ppp, as eficiências de corrente e de remoção determinadas foram, respectivamente, 45% e 96%, após 30 minutos de eletrólise a –0,90 V, enquanto para 60 ppp foram encontrados 33% e 99%, respectivamente. A voltametria de redissolução anódica com eletrodo de gota pendente de mercúrio foi empregada para monitorar a concentração do íon Cd2+ após cada experimento de eletrodeposição.; The electrodeposition of Cd2+ ion was investigated in pH 4.8 sulfuric-sulfate solutions in the presence of dissolved O2. In potentiostatic conditions, using reticulated vitreous carbon (RVC) electrodes of 30...

Electrodeposition of Zn-Mn alloys from recycling battery leach solutions in the presence of amines

Brito, P. S. D.; Patrício, S.; Rodrigues, L. F.; Santos, D. M. F.; Sequeira, C. A. C.
Fonte: WIT Transactions on Ecology and Environment: The Sustainable World Publicador: WIT Transactions on Ecology and Environment: The Sustainable World
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
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The recovery of metal ions by electrodeposition from solutions resulting from the lixiviation of spent Zn-MnO2 batteries was studied. It was attempted to optimise the electrodeposition process, the selectivity of ion-separation, the morphologic characteristics, and the anticorrosive and galvanic properties of metallic deposits. The simultaneous deposition of zinc and manganese on different ferrous substrates under various experimental conditions was tested. This allowed us to access the efficiency of the electrodeposition, the morphology and composition of the metallic deposits, as well as their performance as galvanic coating layers. The effect of amine additives, namely, of methylamine and ethylenediamine, on the properties of the coatings was also studied. It was shown that the amines with buffering or passivating effects improve the simultaneous deposition of Mn.

Electrodeposition of black chromium from CR(III) ionic liquid solution

Eugénio, S.; Rangel, C. M.; Vilar, Rui
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 21/09/2009 ENG
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Black chromium is an important coating material used in solar thermal systems as a spectrally selective surface. This coating is usually obtained by electrodeposition from sulphate free chromium (VI) aqueous solutions which represent a health and environmental hazard due to the presence of Cr(VI), a known toxic and carcinogenic agent. Recent developments in green chemistry have shown that ionic liquids can be used as electrolytes, allowing the deposition of a wide range of materials with negligible environmental and health impacts. In the present study, the electrodeposition of black chromium films from a solution of ionic liquid containing chromium (III) has been investigated by cyclic voltammetry and chronoamperometry. Homogeneous and well adherent black Cr films have been obtained on several substrates, by potentiostatic electrodeposition. The films morphology and composition have been characterised by SEM/EDS and GI-XRD.

Kinetic study of the cobalt electrodeposition onto glassy carbon electrode from ammonium sulfate solutions

Rios-Reyes,Clara Hilda; Granados-Neri,Madaí; Mendoza-Huizar,Luis Humberto
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
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We carried out an electrochemical study of the cobalt electrodeposition onto glassy carbon electrode from an aqueous solution containing 10-2 M of CoSO4 + 1 M (NH4)2SO4 at natural pH 4.5. The potentiostatic study indicated a progressive 3D nucleation and growth during the deposition process. The average diffusion coefficient calculated for this system was 2.65 X 10-6 cm² s-1 while the ΔG for the formation of stable nucleus was 6.50 X 10-20 J/nuclei. The scanning electron microscopy images indicated the formation of small and homogeneous nucleus onto GCE of approximately 300 nm.

Electrochemical study about zinc electrodeposition onto GCE and HOPG substrates

Granados-Ner,Madai; Huizar,Luis Humberto Mendoza; Rios-Reyes,Clara Hilda
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
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We carried out an electrochemical study about zinc electrodeposition onto GCE and HOPG substrates from an electrolytic plating bath containing 0.01M ZnSO4 + 1M (NH4)2SO4 at pH 7. Under our experimental conditions the predominant chemical species was the complex [ZnSO4(H2O)5]. The chronoamperometric study showed that zinc electrodeposition follows a typical 3D nucleation mechanism in both substrates. The average dG calculated for the stable nucleus formation was 6.92 x 10-21 J nuclei"1 and 1.35 x 10-20 J nuclei"1 for GCE and HOPG, respectively. The scanning electron microscopy (SEM) images showed different nucleation and growth processes on GCE and HOPG substrates at same overpotential.

Removal of Cd2+ ion from diluted aqueous solutions by electrodeposition on reticulated vitreous carbon electrodes

Tramontina,Jucelânia; Azambuja,Denise S.; Piatnicki,Clarisse M. S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2002 EN
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The electrodeposition of Cd2+ ion was investigated in pH 4.8 sulfuric-sulfate solutions in the presence of dissolved O2. In potentiostatic conditions, using reticulated vitreous carbon (RVC) electrodes of 30, 60 and 100 pores per inch (ppi), high removal efficiency values were achieved in the potential range from --0.90 to --1.10 V for solutions containing 5 and 10 mg L-1 of Cd2+ ion. In this potential range, Cd electrodeposition is a mass transport controlled reaction and the concentration of the metallic ion decays exponentially with time following a pseudo-first order kinetics. For the 30 ppi RVC, the current efficiency and removal efficiency values found were, respectively, 45 % and 96 % for a solution containing 10 mg L-1 of Cd2+ ion after 30 minutes electrolysis at --0.90 V while 33 % and 99% were found for the 60 ppi RVC. The concentration decay of Cd2+ ion in the solution was monitored after each experiment by anodic stripping voltammetry at a hanging mercury drop electrode.

Electrodeposition of Ni-Mo and Fe-Mo alloys from sulfate-citrate acid solutions

Sanches,Luciana S.; Domingues,Sergio H.; Carubelli,Ademir; Mascaro,Lucia H.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2003 EN
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This paper reports on a study of the electrodeposition of Ni-Mo and Fe-Mo alloys on Pt electrodes in a sodium citrate solution at pH 4.0. The alloys were subjected to cyclic voltammetry at different ion concentration ratios to identify their behavior. The electrodeposited coatings were analyzed by SEM, EDX and XRD. The results of the cyclic voltammetry tests indicated the presence of dissolution peaks only with high Ni or Fe ion concentrations. The SEM analysis revealed that the two alloys had dissimilar morphologies and the Ni-Mo alloys were homogeneous and thick. The Mo and O contents were higher in the Ni-Mo than in the Fe-Mo alloys. Anomalous deposition was found to occur in the co-deposition of Ni and Mo.

The influence of electrochemical pre-treatment of B-doped diamond films on the electrodeposition of Pt

Ribeiro,Mauro C.; Silva,Leide G. da; Sumodjo,Paulo T. A.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2006 EN
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The influence of the substrate electrochemical pre-treatment in 0.5 mol L-1 H2SO4 on the Pt electrodeposition on boron-doped diamond, BDD, film electrodes was investigated. Platinum cannot be electrodeposited on a freshly prepared BDD electrode; however, potentiodynamic cycling or anodic potential steps at short times does activate the electrode. Anodic pre-treatment plays a dual role in the behavior of Pt deposition on BDD surfaces: Pt deposition is increased at short-term anodic pre-treatments, whereas at longer pre-treatment times Pt deposition was inhibited. These facts are explained in terms of wettability changes and passivation of the surface. Conversely, the oxide layer formed in these treatments increases the dispersion level of the catalyst.

Electrodeposition of polypyrrole films on aluminum from tartrate aqueous solution

Liu,Andréa S.; Oliveira,Maria A. S.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
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The electrochemical synthesis of polypyrrole films on aluminum surfaces from aqueous solutions containing tartaric acid and pyrrole was performed using cyclic voltammetry and galvanostatic techniques. A mechanism that considers a porous aluminum oxide layer growing in parallel with the polymeric film explains the polypyrrole electrodeposition on aluminum surfaces. The more homogeneous the distribution of pores on the aluminum oxide layer, the smaller is the resistance offered to the polypyrrole film growth. Polypyrrole films deposited by cyclic voltammetry are much less uniform than those galvanostatically formed. Polymeric films galvanostatically deposited at higher current densities were more susceptible to overoxidation processes than those films formed at lower current densities, as demonstrated by FTIR analyses. Furthermore, films formed at low current density perform better on protecting aluminum surfaces against corrosion.

Electrodeposition of ZnO from DMSO solution: influence of anion nature and its concentration in the nucleation and growth mechanisms

Riveros,Gonzalo; Ramírez,Daniel; Tello,Alejandra; Schrebler,Ricardo; Henríquez,Rodrigo; Gómez,Humberto
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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The influence of the anion nature and its concentration in the electrodeposition of ZnO onto a gold electrode from dimethylsulfoxide (DMSO) solutions was studied. Voltammetric experiments revealed important changes in the zinc oxide electrodeposition process depending on the employed anion as electrolyte. From chronoamperometric experiments, the corresponding current-time curves were fitted with different nucleation and growth mechanism models. The analysis of these results showed changes from an instantaneous to a progressive growth when the solution composition was changed from ZnCl2 to ZnCl2 + LiCl. The change of the mechanism is associated to the adsorption of chloride ion on the active sites of the electrode surface when LiCl is present in the solution.

Multiparticle biased diffusion-limited aggregation with surface diffusion: A comprehensive model of electrodeposition

Castro, Mario; Cuerno, Rodolfo; Sánchez, Angel; Domínguez-Adame, Francisco
Fonte: The American Physical Society Publicador: The American Physical Society
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em /07/2000 ENG
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We present a complete study of the multiparticle biased diffusion-limited aggregation (MBDLA) model supplemented with surface diffusion (SD), focusing on the relevance and effects of the latter transport mechanism. By comparing different algorithms, we show that MBDLA + SD is a very good qualitative model for electrodeposition in essentially the whole range of current intensities provided one introduces SD in the model in the proper fashion. We have found that the correct procedure involves simultaneous bulk diffusion and SD, introducing a time scale arising from the ratio of the rates of the two processes. We discuss in detail the different morphologies obtained and compare them to the available experimental data with very satisfactory results. We also characterize the aggregates thus obtained by means of the dynamic scaling exponents of the interface height, allowing us to distinguish several regimes in the mentioned interface growth. Our asymptotic scaling exponents are again in good agreement with recent experiments. We conclude by discussing a global picture of the influence and consequences of SD in electrodeposition.; Work at GISC was supported by DGES (Spain) Grant No. PB96-0119 and CAM Grant No. 07N/0034/98.; 13 pages, 20 figures.-- PACS nrs.: 05.40.-a...

Electrodeposition of Tin from Tartrate Solutions

Torrent-Burgués,J.; Guaus,E.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 EN
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The electrodeposition of tin in presence of tartrate ions has been analysed by electrochemical techniques, mainly chronoamperometry, and by scanning electron microscopy (SEM). The obtained values of nucleus density with both techniques have been compared and discussed. The electrodeposition process follows an instantaneous nucleation with 3D growth under diffusion control at the initial times of the process, but a second nucleation process occurs at higher times. The influence of tartrate and of agitation conditions is also inferred from the crystal morphology.