In Situ Electrochemical Measurements in the Nanoaquarium

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1973

Physical Review Letters, 1998

The lateral extension of electrochemically induced surface modifications is usually determined by the macroscopic size of the electrodes and the diffusion length of the reacting species. To overcome this constraint, we conducted an electrochemical reaction far from equilibrium. We applied short voltage pulses (#100 ns, up to 64 V) to a scanning tunneling microscope tip while imaging a Au(111) surface in concentrated electrolytes. They lead either to hole formation by anodic dissolution of the Au or to cathodic deposition of Cu islands (in the Cu 21 containing electrolyte), both of nanometer extension. [S0031-9007(98)

Russian Journal of Electrochemistry, 2000

The kinetics of formation of copper adlayer, three-dimensional nucleation, and the deposit growth on polycrystalline platinum and glassy carbon in the 0.5 M H 2 SO 4 + 10 mM CuSO 4 + (0-2) M acetonitrile (AcN) solutions at the cathodic overvoltages is studied using the methods of cyclic voltammetry and potentiostatic current transients on a ring-disc electrode. At [AcN] = 2 M, the process of formation of copper adatoms on platinum is significantly retarded. In the solutions with high contents of AcN, the processes of Cu + ion production, the formation of their complexes with acetonitrile, hydrogen evolution, copper nucleation, and the deposit growth proceed in parallel. The contribution of any process to the overall current depends on the amount of adsorbed AcN at the surface of substrate and copper deposit and on the electrode potential. At [AcN] = 2 M, an increase in the cathodic overvoltage to 0.32 V leads to an abnormal increase in the current of Cu + ion production on platinum, which is caused by insufficiently rapid formation of copper atoms in the reduction of Cu + ( AcN ) x complexes.

Journal of Electroanalytical Chemistry, 2007

ChemistryOpen, 2015

Recent progress in the theory and practice of voltammetry is surveyed and evaluated. The transformation over the last decade of the level of modelling and simulation of experiments has realised major advances such that electrochemical techniques can be fully developed and applied to real chemical problems of distinct complexity. This review focuses on the topic areas of: multistep electrochemical processes, voltammetry in ionic liquids, the development and interpretation of theories of electron transfer (Butler-Volmer and Marcus-Hush), advances in voltammetric pulse techniques, stochastic random walk models of diffusion, the influence of migration under conditions of low support, voltammetry at rough and porous electrodes, and nanoparticle electrochemistry. The review of the latter field encompasses both the study of nanoparticle-modified electrodes, including stripping voltammetry and the new technique of 'nano-impacts'.

Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1973

Analytical Chemistry, 2008

We have developed a new imaging method for scanning electrochemical microscopy (SECM) employing fast-scan anodic stripping voltammetry (ASV) to provide sensitive and selective imaging of multiple chemical species at interfaces immersed in solution. A rapid cyclic voltammetry scan (100 V/s) is used along with a short preconcentration time (300-750 ms) to allow images to be acquired in a normal SECM time frame. A Hg-Pt film electrode is developed having an equivalent Hg thickness of 40 nm that has good sensitivity at short preconcentration times and also retains thin-film behavior with highspeed voltammetric stripping. Fast-scan anodic stripping currents are shown to be linear for 1-100 µM of Pb 2+ and Cd 2+ solutions using a preconcentration time of 300 ms. SECM images showing the presence of Pb 2+ and Cd 2+ at concentrations as low as 1 µM are presented. In addition, a single ASV-SECM image is shown to produce unique concentration maps indicating Cd 2+ and Pb 2+ , generated in situ from a corroding sample, while simultaneously detecting the depletion of O 2 at this sample. The transient voltammetric response at the film electrode is simulated and shows good agreement with the experimental behavior. We discuss the behavior of images and concentration profiles obtained with different imaging conditions and show that mass-transport limitations in the tip-substrate gap can induce dissolution. ASV-SECM can thus be used to detect and study induced dissolution not only at bulk metal surfaces but also on underpotential deposition layers, in this case Cd and Pb on Pt. In addition, we discuss how surface diffusion phenomena may relate to the observed ASV-SECM behavior.

Physical Review A, 1991

We report an extensive study of electrochemical deposition of copper with growth under galvanostatic conditions and parallel geometry. In such conditions a clear understanding of the origin of the ramified deposit and of its growth speed is possible, at least in the case of dense morphology. We confirm that this morphology belongs to a steady-state regime where growth can be modeled as the displacement of a Hat strip of nearly equipotential copper. The growth velocity is exactly the drift velocity of the anions, which is proportional to the current density. We also show that the mass of the deposit does not depend on the speed at which it was grown but only on the concentration of salt in the bulk of the electrolyte. We compute the modifications in concentration profiles and in the electric field due to pH changes during growth.

2019

The Journal of Physical Chemistry B, 2005

The electroformation of Cu-Se phases, obtained by selenizing a thin film of copper deposited on the quartz/ gold electrode system, was studied with an electrochemical quartz crystal microbalance (EQCM) and by cyclic voltammetry (CV) in an alkaline solution (0.05 M Na 2 B 4 O 7) containing selenide ion. Potentiodynamic parameters showed that the formation of the initial Cu-Se phases (Cu 2-x Se/Cu 3 Se 2) is ruled by an irreversible diffusion controlled mechanism, where a first electron transfer is the rate-determining step. A CV study was also performed with a bulk copper electrode in 1 M NaOH solution containing selenide ion. The deconvolution of the anodic and cathodic I/E profiles corresponding to the electroformation and electroreduction of the Cu-Se film formed allowed us to establish that, depending on the anodic potential limit of the potentiodynamic scan, the Cu-Se phases formed were either a mixture of Cu 2-x Se/Cu 3 Se 2 or Cu 2-x Se/Cu 3 Se 2 /CuSe. An EQCM study showed that, during the initial stage of Cu-Se phase electroformation, water molecules were released from the electrode. In advanced stages of the process, when the electrode was completely covered by Cu-Se compounds, selenide anions were adsorbed on the formed phase. When the anodic potential limit was extended to-0.2 V, copper oxide compounds were formed. The analysis of the cathodic charge related to Cu-Se phase electroreduction and Energy Dispersive X-ray Spectroscopy (EDXS) analysis confirmed that when the anodic limit was-0.8 V, a mixture of different Cu-Se phases was formed. A I/t transient study performed with a bulk copper electrode in alkaline solution containing selenide established that the nucleation and growth mechanism (NGM) of the Cu-Se phases takes place through an initial bidimensional-instantaneous nucleation (IN2D), followed by four bidimensional-progressive nucleations (PN2D). These results and atomic force microscopy (AFM) experiences supported that the growth of the Cu-Se films occurs through a layer-bylayer mechanism.