The effect of concentration on the electrocrystallization mechanism for copper on platinum ultramicroelectrodes

Abstract

O mecanismo de eletrocristalização de cobre sobre ultramicroeletrodos de Pt foi estudado por voltametria cíclica, cronoamperometria e microscopia de força atômica ex situ em soluções ácidas contendo diferentes concentrações de Cu 2+. Para análise dos transientes potenciostáticos utilizouse um modelo desenvolvido em nossos laboratórios que leva em consideração a difusão esférica para ultramicroeletrodos na forma de disco. Uma mudança mecanística de nucleação progressiva para instantânea foi observada com o aumento da concentração de íons Cu 2+ de 0,01 para 0,1 mol dm-3. A forma e a distribuição dos núcleos sobre a superfície do eletrodo foram investigados por microscopia de força atômica. A dependência da taxa de formação dos núcleos com o potencial de salto foi analisada em termos da teoria atomística da eletrocristalização e os resultados obtidos sugerem a presença de um único átomo de cobre no núcleo crítico. The mechanism of copper electrocrystallization on Pt ultramicroelectrode surfaces has been studied by cyclic voltammetry, chronoamperometry and ex situ atomic force microscopy in acid solutions containing different Cu 2+ concentrations. To analyze the potentiostatic transients a new model developed in our laboratories that takes into account spherical diffusion towards a disc-shaped ultramicroelectrode was used. A mechanistic change from progressive to instantaneous nucleation was observed when the Cu 2+ concentration was increased from 0.01 to 0.1 mol dm-3. The shape and distribution of the nuclei formed on the surface were investigated by AFM. The dependence of the nucleation rate with potential was analyzed in terms of the atomistic theory of electrocrystallization and the results suggest the presence of only one copper atom in the critical nucleus.

Electrochemical processes of nucleation and growth of hydroxyapatite on titanium supported by real‐time electrochemical atomic force microscopy

“…27 For example, a small decrease of 70 mV versus SCE in the cathodic overpotential has been reported to result in an increase by more than one order of magnitude in t m for electrocrystallization of Cu on Pt. 28 Next, the electrochemical and chemical reactions involved in the deposition of HAP are summarized. When a voltage is applied, several electrochemical reactions may occur: Reactions (3.1) through (3.6) all lead to a local increase in pH within the diffusion layer.…”

The mechanical and rheological behavior of the PA/TPU blend with POE‐g‐MA modifier

“…In addition, one should recall that the model of Scharifker and Hills24 lacks a description of the dynamic interaction between chemical species in the solution and neglects the influence of reduction/oxidation rates and of external variables such as the applied potential 27. For example, a small decrease of 70 mV versus SCE in the cathodic overpotential has been reported to result in an increase by more than one order of magnitude in t m for electrocrystallization of Cu on Pt 28…”

Electrochemical sensors: a powerful tool in analytical chemistry

“…Machado, Avacca and coworkers [137][138][139] have reviewed some theoretical aspects and studied the utilization of Pt, Co, or Ni-Co microelectrodes (UME) to characterize copper electrocrystallization and hydrogen evolution. Mori and Bertotti 140 have investigated the chemical reaction between nitrite and iodide by using microelectrodes and Cavalheiro and co-workers 141 have shown the application of nanostructured carbon fiber disk microelectrodes for determination of adenosine and uric acid in physiological buffers.…”