Quasiperiodic behavior in the electrodeposition of Cu/Sn multilayers: extraction of activation energies and wavelet analysis

Menezes, Laura; Parma, Eduardo; Machado, Eduardo G.; Nagao, Raphael

doi:10.1039/c9cp03605a

Cited by 6 publications

(2 citation statements)

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“…In electrochemical systems, the oscillatory dynamics strongly depends on the applied current besides the temperature, among other parameters. ,,,− On the other hand, the applied current density j is usually different in each galvanostatic experiment because it is adjusted by a normalization process to minimize the current effect on oscillatory characteristics and facilitate experimental comparison . Alternatively, the influence of temperature on the oscillatory behavior can be analyzed simultaneously with the effect of the applied current.…”

Section: Resultsmentioning

confidence: 99%

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

et al. 2020

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In this work, the effect of temperature on the electro-oxidation of formic acid on platinum was modeled and numerically investigated. Numerical simulations were carried out using an electrokinetic model recently validated through voltammetric and galvanostatic experiments. We show that the intrinsic electrocatalytic activity of the working electrode for the overall electrochemical reaction can hardly be interpreted from the apparent activation energy due to the complexity of the reaction scheme. A detailed analysis is possible through the estimation of the activation energies determined from the individual rate coefficients. By doing so, we observed that the direct pathway, with an activation energy of 91 kJ mol–1 at 0.40 V and 72 kJ mol–1 at 0.80 V, is the energetically easiest pathway for the formation of CO2 in the proposed reaction scheme. Regarding the self-organized potential oscillations under the galvanostatic regime, our model was able to reproduce experimentally observed results including the phenomena of temperature compensation and overcompensation. Importantly, we have introduced a formalism to classify the elementary steps that contribute to the increase and decrease of the oscillatory frequency in electrochemical systems. Our results shed light on the understanding of the temperature dependence of complex electrocatalytic reactions, and the developed methodology was proven to be robust and of general applicability.

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Section: Resultsmentioning

confidence: 99%

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

et al. 2020

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“…Thereafter, it is possible to design a nanostructured material by suitable changes in the controlling parameters of the system which strongly affect the dynamics. Usually, these changes are focused on variations in the applied current and/or potential, , temperature, − electrode rotation rate, , etc. It would be very interesting, however, if the chemical structure or function of the reactants could be altered to induce an autonomous growth of a target material, giving rise to a bottom-up synthesis approach.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Ligands in Cu(II) Complexes on the Oscillatory Electrodeposition of Cu/Cu₂O

et al. 2020

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Oscillatory electrodeposition reactions have been utilized to create nanostructured materials under the microscale and nanoscale. This alternative method of synthesis, when compared to the traditional step-by-step synthesis procedure, takes advantage of the self-organizing processes that do not require any external control or template-based support, resulting in materials with higher complexity in terms of structure and composition. Nanolayers made of Cu and semiconductor composites, such as Cu/Cu2O, can be finely tuned by controlling ordinary period-one oscillations in the cathodic deposition. As the reaction media is alkaline, a complexing agent is commonly added in the solution to prevent the precipitation of the copper ions as hydroxides. Lactate and tartrate molecules are two α-hydroxy carboxylate organic ligands extensively used for this aim. Although some studies have shown the electrochemical synthesis of Cu/Cu2O nanolayers, no grounded discussion about the influence of the chemical nature of the ligands on the oscillatory reaction has been investigated so far. Here, we provide a well-detailed and rigorous study of the effect of both ligands in the electrodeposition of Cu/Cu2O under galvanostatic control, accurately mapping differences in the oscillation period and amplitude. On the basis of recent advances on the understanding of the copper complex structures, we attributed a distorted tetrahedral structure with four monodentate lactate ligands linked to the Cu2+ central ion ([Cu(Lac)4]2–) and a distorted square-planar coordination of the tartrate’s deprotonated alkoxide groups, forming a chelate ([Cu(TartH–2)2]6–), as the species that have a buffering effect on the oscillatory mechanism and, consequently, can control the extension of the oscillation period and amplitude. In this matter, the tartrate complex should have a higher buffering capacity to prolong the period and decrease the amplitude. More importantly, we unequivocally show that a surface blocking effect due to the adsorption reactions cannot be neglected in the mechanism description. The adsorption of the tartrate anions and its complexes has, also as an outcome, period enlargement and amplitude shrinkage, as compared to that of the lactate. Hence, both mechanisms seem to operate in the adjustment of the dynamic characteristics of the oscillatory electrodeposition of Cu/Cu2O.

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Self‐Organization in Electrochemical Synthesis as a Methodology towards New Materials

et al. 2020

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Despite its potential, self‐organization as a methodology for the synthesis of materials has not been developing at the pace required for the ample scale synthesis of materials with more complex structures. As there is an environmental demand for a fast change in the energy matrix, away from fossil fuels, by using materials with more complex composition and structure, this topic has been gaining potential. As complexity can be observed in many different fields of science, from biology to physical chemistry, this Review intends to focus on recent advances of self‐organization in electrochemical systems. To provide a deeper understanding of the literature being reviewed, the fundamentals of nonlinear dynamics in electrochemistry is discussed, based on classical literature. Following this, two electrochemical processes in which self‐organization is observed will be reviewed, namely electrodeposition and electrodissolution. In the final section, self‐organization is presented as a perspective for applied systems, where self‐organization is employed for the synthesis of materials of technological importance. This Review intends to reignite the debate on how self‐organization could be used to produce more complex materials than the traditional step‐by‐step approach could achieve.

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Quasiperiodic behavior in the electrodeposition of Cu/Sn multilayers: extraction of activation energies and wavelet analysis

Abstract: The oscillatory electro-deposition of Cu/Sn in the presence of a surfactant shows quasiperiodic behavior, which is described by the coupling between a mainly activation and a mainly diffusion-controlled processes.

Cited by 6 publications

References 51 publications

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

Influence of the Ligands in Cu(II) Complexes on the Oscillatory Electrodeposition of Cu/Cu₂O

Self‐Organization in Electrochemical Synthesis as a Methodology towards New Materials

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Quasiperiodic behavior in the electrodeposition of Cu/Sn multilayers: extraction of activation energies and wavelet analysis

Abstract: The oscillatory electro-deposition of Cu/Sn in the presence of a surfactant shows quasiperiodic behavior, which is described by the coupling between a mainly activation and a mainly diffusion-controlled processes.

Cited by 6 publications

References 51 publications

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

Thorough Analysis of the Effect of Temperature on the Electro-Oxidation of Formic Acid

Influence of the Ligands in Cu(II) Complexes on the Oscillatory Electrodeposition of Cu/Cu2O

Self‐Organization in Electrochemical Synthesis as a Methodology towards New Materials

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Product

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Influence of the Ligands in Cu(II) Complexes on the Oscillatory Electrodeposition of Cu/Cu₂O