Electrodeposition surface morphology

Figure 7.6. SEM of the electrodeposited CIGS precursor film (a) surface morphology and (b) cross section. 

Pure nickel electrodeposits with macropores were prepared from electrolytic solutions of 0.2 mol dm NiCl2 and NH4CI with concentrations varying between 0.25 and 4 mol dm [64]. The effects of the electrodeposition current density and the NH4CI concentration on the surface morphology were determined. Surface area, faradaic efficiency, and fractal dimension... 

The same mechanism of zinc electrodeposition on the GC electrode was observed in sulfate, chloride, and acetate ion solutions [227]. The anions mainly affected the nucleation densities during zinc deposition, which resulted in a different surface morphology. The nucleation rate constant was the same in the chloride and sulfate solutions and was equal to 1.22 x 10 s h In the presence of acetate and chloride ions, the deposited zinc film tends to grow in a multilayered pattern, while in sulfate solution, the zinc deposition forms irregular grains. A new approach to the estimation of zinc electrocrystallization parameters on the GC electrode from acetate solutions was described by Yu et al. [228]. 

CdSe thin films and CdSe nanocrystal layers were electrodeposited on Ti or ITO substrates in solutions containing CdS04 and H2Se03 at pH 2.5 [188, 189]. The influence of different deposition potentials on the surface morphology and crystal structure of CdSe Aims was studied. 

The SEM micrograph of Figure 12.7(a) shows the surface morphology of a deposited aluminum layer obtained galvanostatically at a current density of—5 mAcrn-2 for 2h in the upper phase of the biphasic mixture [EMIM] TFSA/6M AICI3 at room temperature. Prior to Al electrodeposition, the electrode was anodically polarized at a potential of 1V (vs. Al) for 2 min. As seen, the deposited Al layer is dense and contains crystallites in the micrometer regime. 

An important extension of these techniques is when the substrate is made into an electrode in a small electrochemical cell, so that the change in surface morphology of the substrate can be monitored with time. In this way, for example, direct visualisation of electrodeposition at the sub-microscopic level can be seen in real time, both nucleation and growth phases, e.g., the electrodeposition of copper in media with and without organic additives [42]. 

Unfortunately, the electrodeposition of metals summarized in Table 4 is accompanied by increased HTSC degradation under cathodic polarization [53, 55]. In nonaqueous media, electrocrystallization processes can be inhibited due to the peculiarities of the intermediate Cu+ species solvation [286]. Moreover, the surface morphology of deposits can be adversely affected by the formation of dendrites this can be overcome by the addition of a brightening agent [497]. 

It should be mentioned, however, that surface inhomogeneities of different dimensionality (cf. Section 2.1) significantly influence the kinetics of metal electrodeposition and the time-dependent surface morphology. Therefore, an exact analysis of corresponding EIS spectra is rather difficult. The necessary presumptions of stationarity and linearity for EIS measurements and quantitative interpretation of EIS data are often violated. The lack of direct local information on surface dynamics strongly hinders a quantitative analysis of the impedance behavior of time-dependent systems. Such considerations have been mainly disregarded in previous EIS data interpretations. In future, a combination of EIS measurements with in situ local probe... 

There are two basic problems in activation of inert substrates by electrodeposition first, the effect of the structure of the active surface film on the transformation of electrode from inert to active one7 and second, effect of the surface morphology on the polarization characteristics of activated electrodes.8,9 Obviously, in the last case, the nature of the initial substrate is not important. The analysis of both of them is the aim of this chapter. It will be performed for the cathodic reactions. Obviously, the corresponding analysis for the anodic processes can be performed in the similar way. 

In Chapter 4 by Popov et al., the aspects of the newest developments of the effect of surface morphology of activated electrodes on their electrochemical properties are discussed. These electrodes, consisting of conducting, inert support which is coated with a thin layer of electrocatalyst, have applications in numerous electrochemical processes such as fuel cells, industrial electrolysis, etc. The inert electrodes are activated with electrodeposited metals of different surface morphologies, for example, dendritic, spongy-like, honeycomblike, pyramid-like, cauliflower-like, etc. Importantly, the authors correlate further the quantity of a catalyst and its electrochemical behavior with the size and density of hemispherical active grain. 

Jiang et al. studied the electrodeposition and surface morphology of aluminum on tungsten (W) and aluminum (Al) electrodes from 1 2 M ratio of [Emim]CI/AlCl3 ionic liquids [165,166]. They found that the deposition process of aluminum on W substrates was controlled by instantaneous nucleation with diffusion-controlled growth. It was shown that the electrodeposits obtained on both W and Al electrodes between -0.10 and -0.40 V (vs. AI(III)/A1) are dense, continuous, and well adherent. Dense aluminum deposits were also obtained on Al substrates using constant current deposition between 10 and 70 mA/cm. The current efficiency was found to be dependent on the current density varying from 85% to 100%. Liu et al. showed in similar work that the 20-pm-thick dense smooth aluminum deposition was obtained with current density 200 A/m for 2 h electrolysis [167],... 

Jiang T, Cholher MJ, Brym B (2006) Electrodeposition of aluminum from ionic liquids part i - electrodeposition and surface morphology of aluminum from etluminium chloride ([EMIm] Cl) ionic liquids. Surf Coat Technol 201 1-9... 

Before specifically dealing with coherent x-ray imaging, its foundations, and its advantages, we note that alternate experimental solutions were used to tackle these problems. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) probe the surface morphology and the overall microstructure of metal electrodeposits. However, they do not work in real time they are used to analyze the final products after the end of the growth. 

Nanocrystalline and amorphous nickel-boron films with different boron content were prepared by electrodeposition. Ability of various boron-containing compounds to be a source of boron was studied. Effects of boron content on the crystallite size, surface morphology, microhardness and wear resistance of the films were investigated. It was shown that the Ni-B films containing less than 14 at. % of boron had the nanocrystalline structure. The films became amorphous at boron content more than 14 at. %. Boron incorporation into nickel film and increasing the content of boron resulted in a decrease of the crystallite size, extension of grain boundaries and considerable increase in microhardness and wear resistance. 

Electrodeposition of silicon can be achieved from PC baths containing tetra-alkylammonium chlorides and SiHClj as the Si source Deposits on a variety of materials including low-cost substrates such as the Ti-6 Al-4 V alloy or coated fused silica were made. Both surface morphology and current decay resulting from the increase of electrical resistance of the growing Si film can be controlled by the cation size of the supporting electrolyte, R NCl. Bound hydrogen (SiH or SiH) can be driven off at 470 °C. The amorphous Si film exhibits photoconduction and photovoltaic properties and offers an inexpensive route for solar cell applications. 

Surface morphology of the electrodeposited PPDOT-Et2 film observed by SEM is characterized as a random and highly porous network of polymer fibers, as shown in Figure 3.9. The polymer fiber size tends to depend on the total charge... 

The use of CP-coated electrodes for metal electrodeposition, instead of the typical conducting (metal, glassy carbon etc.) substrates, results in the interference in this process of various specific factors that closely relate to the intrinsic propertiesof CPs. Among them are the initial oxidation state of the CP material, its surface morphology and surface chemical state, and also bulk characteristics, such as porosity and metal-polymer chemical interactions. These factors are often inter-related and therefore it is difficult to differentiate clearly their effect on the characteristics of the obtained metal deposit. 

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