Revestimentos produzidos a partir de ligas de Cu-Sn apresentam grande interesse em função de suas propriedades, originando uma grande capacidade de aplicação industrial, especialmente em indústrias de componentes e materiais eletrônicos. Tais ligas também têm sido comercialmente utilizadas como revestimentos em metais diferentes, como o aço, para protegê-los contra a corrosão e melhorar sua aparência. Na presente dissertação, técnicas de voltametria cíclica, cronoamperometria e voltametria de varredura anódica linear foram utilizadas para o estudo dos processos de deposição de Cu e/ou Sn a partir de dois conjuntos de soluções contendo CuCl2.2H2O e SnCl2.2H2O nas razões de Cu:Sn = 1:10 e 10:1, além de Na3C6H5O7 1,00 mol/L, em pH = 6,0. As curvas de voltametria cíclica realizadas sobre o eletrodo de grafita foram utilizadas para o cálculo das constantes de equilíbrio dos complexos de ambos os metais com citrato de sódio, bem como na determinação dos potenciais catódicos aplicados nos ensaios de cronoamperometria. Após a deposição da liga nos potenciais estipulados para cada uma das duas soluções, os revestimentos de liga Cu-Sn foram ressolubilizados em solução de NaNO3 0,5 mol/L, empregando varredura anódica linear para a avaliação de suas composições químicas. Os resultados iniciais mostraram que a variação da concentração de Cu (II) e do potencial aplicado influenciaram no teor de cobre na liga. Contudo, percebeu-se que o teor de estanho não sofreu grandes variações, independente das concentrações das soluções e do potencial aplicado. Na solução com maior concentração de cobre foram alcançados teores dos metais na liga em maior proximidade com o da liga de bronze comercial. Com base nesses resultados, foram produzidos revestimentos de ligas sobre substrato de aço carbono, a partir de soluções contendo CuCl2.2H2O e SnCl2.2H2O na razão de 10:1, empregando a técnica de cronoamperometria potenciostática. Quatro diferentes valores de potencial (-0,39V, -0,67V, -1,00V, -1,20V e -1,94V vs. Ag/AgClsat.) foram aplicados, obtendo-se camadas cujas colorações variaram do rosa claro ao marrom escuro, sempre sem brilho. A eficiência de corrente catódica (Ef) decresceu conforme o potencial aplicado se tornou mais negativo. Nesta mesma direção, verificou-se um aumento do teor de estanho na liga depositada e menores tamanhos de grão. Porém, quando o potencial tornou-se mais negativo (-1,20V e -1,94V), observou-se a presença de cristalitos de diferentes tamanhos e de dendritos. Revestimentos com melhores resistências à corrosão em solução de NaCl 0,5 mol/L foram produzidos nos potenciais de -1,00V e -1,20V, cujas composições foram 99,40 % m/m Cu / 0,60 % m/m Sn e 97,70 % m/m Cu / 2,30 % m/m Sn, respectivamente. As análises por DRX permitiram verificar que estes revestimentos eram constituídos, principalmente, da fase α-CuSn

The performance of axial view ICP OES and ICP-MS techniques were compared through the determination of As, Fe, Mn, Pb, Sb and Sn in electrolytic copper. Samples were prepared by two procedures: 1. Total dissolution with 5 % v/v HNO3 and 2. Dissolution with 1.4 % v/v HNO3 plus 2.0 % v/v H2SO4, followed by separation of the Cu by electrodeposition. The methods were applied for the analysis of standard copper solutions, using calibration against aqueous solutions with or without the addition of Cu. The results obtained by the two techniques were similar, but the separation of Cu from the sample matrix proved to be more adequate for practical reasons.

In spite of selenide semiconductors having a wide application area, TlCu2 Se2 (TCSe) is poorly studied and its synthesis by non-vacuum or thermic methodology in film form is non-existent. Generally, the main problems of applying these TCSe compounds are related to complicated single phase growth, and the great time consuming and non-scalable fabrication method. In this work, the facile, fast, scalable and new electrochemical deposition of this material was proposed as a workaround for these main problems and obtaining single phase thin film. Thus, the electrodeposited Tlx Cu3 - x Se2 films were characterized by scanning electron microscopy, X-ray diffraction (with Rietveld refinement) and energy dispersive X-ray spectroscopy. They showed interesting variation of composition (x =1.1, 1.2, and 1.25) and morphology as function of the electrodeposition potential, electrolytic bath temperature and thermal treatment.

This work presents a voltammetric method for Zn2+ determination in antiseptic dusting powder and multivitamin commercial samples, combining an alkaline extraction using NaOH aqueous solution with a carbon paste electrode chemically modified with Bi anchored on Amberlite® IR120 ion exchange resin (CPEAmb/Bi). The best conditions for electrode preparation were: 10% (m/m) of Amberlite® IR 120; 30 s Bi3+ accumulation time (open circuit) in 0.5 mmol L-1 Bi3+ solution prepared in 0.1 mol L-1 acetate buffer (pH = 5.5). The analytical curve for Zn2+ using the CPEAmb/Bi presented linear range from 0.05 to 8.2 µmol L-1 and the limit of detection was 10 nmol L-1. The voltammetric method was simple, fast, efficient and low-cost for the Zn2+ determination in antiseptic dusting powder and multivitamin samples.

Hydrogen is seen as a future energy carrier that will assist the global energy fuel demand. However, it is still necessary to study efficient and inexpensive catalysts that can be used on a large scale to make this technology practical. In this paper the electrodeposition of molybdenum disulfide (MoS2) film on titanium (Ti) substrate was performed by cyclic voltammetry and the film was evaluated for hydrogen evolution reaction (HER). The deposition optimized conditions was 25 cycles and 4 mmol L-1 (NH4)2[MoS4] in 0.1 mol L-1 NaClO4 solution. The film was characterized from X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and they showed an amorphous structure and high catalytic activity for HER. The Tafel slope was 85 mV dec-1 and overpotential at -10 mA cm-2 was -139 mV showing that Ti substrate compared with fluorine-tin doped oxide (FTO) substrate favored the HER and electroactivity of MoS2 films.

Ni–W–P electrodeposits were synthesized in a Hull cell in order to simulate the obtainment under industrial conditions. Complete coverage of panels was accomplished by applying total currents of 1.0 and 2.0 A. Panels obtained with a current of 1.0 A appeared brighter. The best compositional uniformities, as determined by Energy Dispersive Spectrometer (EDS) occurred in the current density ranges of 0.6 to 3.0 A dm−2 and 1.6 to 6.0 A dm−2 obtained with 1.0 and 2.0 A, respectively. However, the best morphological characteristics, as determined by Scanning Electro Microscope (SEM), were observed in those obtained with a total current of 1.0 A. Analysis of corrosion resistance by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Linear Polarization (PLP) in NaCl have shown significant variations in the amount of corrosion potential, polarization resistance, and even total impedance. The alloys exhibited amorphous character (XRD) and crystallized above 400 °C to Ni and Ni3P phases, and possibly Ni–W, with a subsequent increase in hardness. The results suggest that under industrial conditions, current density variations due to the large and complex geometric shapes of substrates lead to formation of distinct alloys. Furthermore, these materials are potential substitutes for chromium deposits in many applications.

Chemically modified electrodes have been studied to obtain new and better electrochemical sensors. Transparent conductive oxides, such as fluorine-doped tin-oxide (FTO), shows electrical conductivity comparable to metals and are potential candidates for new sensors. In this work, FTO was modified by gold electrodeposition from chlorine-auric acid solution using cyclic voltammetry (CV) technique. A set of different materials were produced, varying the scan number. Scanning electron microscopy and electrochemical impedance spectroscopy were performed for the characterization of electrodes surfaces. From this analysis was possible to observe the resistive, capacitive and difusional aspects from all kind of modified electrodes produced, establishing a relationship between this parameters and the scan number. The electrode with 100 scans of CV presented better characteristics for an electrochemical sensor; it has the lowest global impedance and rising of capacitive behavior (related to electrical double layer formation) at lower frequencies. This electrode was tested for paracetamol and caffeine detection. The results showed a high specificity, decreased oxidation potential (0.58 V and 0.97 Vvs. SCE, for paracetamol and caffeine, respectively) and low detection limits (0.82 and 0.052 µmol L-1).

In this paper, we show the development of a LabVIEW algorithm able to apply the delayed feedback control on oscillatory electrochemical reactions. The coupling of the control and the experiments was carried out by a real-time apparatus, measuring the faradaic current and, in sequence, applying a calculated circuit voltage as an analog output. The setup was used to control the oscillatory Cu/Sn electrodeposition dynamics, used as a model-system, and the results clearly demonstrate the control accuracy. Overall, the code may be a great tool for the controlled synthesis of nanomaterials in different oscillatory electrodeposition reactions, as it offers the ability to control the composition and structure of the deposit by fine tuning the dynamic properties.

Nickel was electrodeposited from choline chloride (ChCl)-based deep eutectic solvents (DESs) containing ethylene glycol (EG) and urea (U) on Cu substrate. The influence of the temperature and of DESs nature was evaluated. The diffusion coefficients of nickel varied from 2.2 × 10-9 to 3.7 × 10-8 cm2 s-1 for ChCl:2U and from 1.3 × 10-8 to 5.8 × 10-8 cm2 s-1 for ChCl:2EG with increasing temperature. The nucleation process of Ni on Cu at 70 °C was determined as instantaneous in ChCl:2EG and progressive in ChCl:2U using Scharifker and Hills model. The SEM characterization showed that with increasing temperature, more compact coatings were obtained. Linear polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion performance of the obtained deposits in 3.5% NaCl. The coatings were more protective as higher the temperature of deposition, with polarization resistance (Rp) values from 3.53 to 19.11 kΩ cm2.

In this manuscript, we report the electrodeposition of nickel-copper alloys in a two steps methodology. Firstly, the copper electrode is oxidized to generate Cu2+ ions followed by the reduction of both Ni2+ and Cu2+. The electrodes were further cycled in KOH to convert the metallic alloy into the respective electroactive hydroxide. This methodology created an electrode with high roughness and distinct electrochemical behavior. The modified electrodes were also characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Finally, the modified electrodes were studied in their supercapacitive properties by galvanostatic charge and discharge curves; the electrodes showed a good specific capacitance of 58 mF cm-2. The results indicated a new strategy using a simple methodology to modified Cu-electrodes to develop supercapacitors at low cost.