Pulsed-potential deposition

Fig. 18.4 Contrast between TiC /WCE composite films electrodeposited by (a) pulsed-potential deposition in a single deposition bath and (b) sequential deposition in different baths [reprinted from Somasundaram et al. (2006), copyright (2006), with permission from Elsevier]...

When cyclic voltammetric growth or pulsed-potential deposition is used, the behavior of the auxiliary electrode at anodic potentials is also important because... 

When cyclic voltammetric growth or pulsed potential deposition is used, the behavior of the auxiliary electrode at anodic potentials is also important because exposure to extreme positive potentials may occur. If easily oxidized (e.g., stainless steel), the release of metal ions into solution can interfere with the polymerization process at the anode. Alternatively, generation of products from water oxidation or organic solvent oxidation can cause problems. This again emphasizes the need to control the reactions occurring at the auxiliary electrode. 

Determination of lead in 70 pL samples of whole blood can be carried out in a few minutes by a procedure including treatment with a matrix-modifying solution containing hydrochloric acid, Hg(II) ions, Triton X-100 and Bi(III) as internal standard. After deposition of lead amalgam on a glassy carbon electrode by a pulsed potential cycle, analysis... 

Based on cathodic electrodeposition of Ti02 and W03 films, de Tacconi and coworkers (2003) provided a method to cathodically electrodeposit Ti02/W03 composite films via the control of a pulsed deposition potential. By mixing the deposition baths for both Ti02 and W03, the authors applied a pulsed potential... 

Anodic stripping voltammetry (ASV) was applied to the determination of copper traces present as Cu(dik)2. The differential pulse technique was used to strip the amalgamated copper from a hanging mercury drop electrode. The experimental variables such as scan rate of electrode potential, deposition potential, deposition time and stirring speed of the solution could be optimized. The linear range of the calibration plot was 0.05-1 (xM and the LOD was 0.014 fiM Cu(II). A method was used for the determination of copper in breast milk and beer as typical examples of application, consisting of minerahzation of the sample, extraction of Cu(II) from the aqueous solution with a 1 M solution of acacH in chloroform and ASV end analysis . 

For their rich potential in various applications described in the previous section, the synthesis and assembly of various ZnO micro and nanostructures have been extensively explored using both gas-phase and solution-based approaches. The most commonly used gas-phase growth approaches for synthesizing ZnO structures at the nanometer and micrometer scale include physical vapor deposition (40, 41), pulsed laser deposition (42), chemical vapor deposition (43), metal-organic chemical vapor deposition (44), vapor-liquid-solid epitaxial mechanisms (24, 28, 29, 45), and epitaxial electrodeposition (46). In solution-based synthesis approaches, growth methods such as hydrothermal decomposition processes (47, 48) and homogeneous precipitation of ZnO in aqueous solutions (49-51) were pursued. 

In the case of silver deposition, the OCP was —680 mV versus SCE after deposition, the nucleation pulse potentials Ej and the deposition time tj and t2 were varied. The growth pulse potential E2 was -700 mV versus SCE. The averaged diameter of the silver cluster deposited was about 200 nm. The samples with particles were taken from the preparation bath and carefully washed and dried in a desiccator. 

The electrodeposition of gold was made in an acidic electrolyte of 0.005 M HAUCI4 per liter. The open circuit potential (OCP) after deposition was +820 mV versus SCE. The pulse potentials were varied between +800 and +600 mV versus SCE. Particles between 10 and 500 nm diameter were prepared. 

The electropolymerization of ferrocene/thiophene conjugates [65] was conducted by oxidation on a Pt electrode and led to the deposition of a monolayer of poly (thiophene). The electropolymerization was performed from several solution systems, such as tetrabutylammonium hexafluorophosphate/acetonitrile and lithium perchlorate/acetonitrile, at a concentration of 0.1 M. Constant potential experiments (+ 2.0 V) for a definite time were used to effect polymerization. Polymerization was also attempted using cyclic voltammetry (repeatedly sweeping from 0.0 to + 2.5 V) and pulse potential (potential stepped from 0.0 to 2.0 V and back to 0.0 V). 

Electrolysis of 10 mM sucrose was performed on a Pt-Pb electrode using a triple-pulse potential programme. The concentration of the precursor salt, Pb(C104)2, was 10 5 M. The first potential pulse, fixed at 0.4 V/RHE during 1 s, is used to adsorb the organic molecule and to deposit in situ the metal adatoms onto the electrode surface. The potential of the oxidation plateau was set to... 

In case of EMM, the normal value of applied pulsed potential across the electrodes, which maintain a narrow gap, is much less and current is in the order of microampere. Pulse frequency is very large, i.e., in the order of megahertz, which minimizes the machining cycle time. During this very small cycle time as well as due to the stagnant nature of electrolyte, it is difficult to overcome the charge transfer resistance, which may lead to deposition of metal ions or sludges on the surface of the microtool or workpiece. 

Wu H-M, Hsu P-F, Hung W-T (2009) Investigation of redox reaction of Ru on carbon nanotubes by pulse potential electrochemical deposition. Diam Relat Mater 18 337-340... 

The electrodeposition process can either occur under potential (potentiostatic deposition) or current (galvanostatic deposition) control. In practice, the common approach is to control the deposition flux (current) in order to obtain the deposit with desired thickness and properties. The electrodeposition under galvanostatic control can be executed as either the constant current process or using some more complex currenttime function profile. In the latter case, the electrodeposition process is commonly called the pulse current deposition and it has been widely used in industrial and academic applications. The typical pulse current function has the simple on/off profile shown in Fig. 11. ... 

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