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Properties and characterization of conductive polymers
Published in Ze Zhang, Mahmoud Rouabhia, Simon E. Moulton, Conductive Polymers, 2018
David L. Officer, Klaudia Wagner, Pawel Wagner
In chronoamperometry (CA), the potential step is applied to the working electrode (Figure 3.4a) and the current is recorded as a function of time (Figure 3.4b). The current response (Figure 3.4b) is controlled by diffusion, and the current magnitude is determined by the geometric area of the electrode. Upon application of each potential step (Figure 3.4a), there is a current “spike” (Figure 3.4b) due to potential-induced reorganization of the molecules adjacent to the electrode surface. Once the electrochemical process starts, the rate of reaction is measured as a current that is controlled by the rate of diffusion of the electroactive species to the electrode surface. The measured current is proportional to the concentration gradient and the continued flux, causing the depletion of electroactive species near the working electrode. This results in a concentration (current) profile decreasing with time. CA is an excellent technique for measuring diffusion coefficients (Galus et al. 1994; Yap and Doane 1982).
Electrochemical Studies in Microemulsions
Published in Promod Kumar, K. L. Mittal, Handbook of Microemulsion Science and Technology, 2018
A battery of techniques are available to characterize the microstructure and also understand the interactions in microemulsions. Tools widely used include dynamic light scattering, nuclear magnetic resonance, neutron scattering, small-angle X-ray scattering, and fluorescence spectroscopy. Some of these topics appear elsewhere in this book. Electrochemical techniques provide a complementary approach that is simple, fast, and inexpensive for characterization of microemulsions [24]. Any electrochemical technique that allows the determination of the diffusion coefficient of an electroactive substance can, in principle, be used for measuring diffusion in micellar and microemulsion systems [24–27]. A predetermined concentration of an electroactive probe is dissolved in the surfactant system, and an apparent diffusion coefficient of the aggregate (micelle or microemulsion droplet) is measured. The information obtained depends on the nature of the electroactive probe, its relative partitioning between the continuous and discontinuous pseudophases, and interactions. Electrochemical techniques used for such studies include polarography, cyclic voltammetry (CV), rotating disk voltammetry (RDV), chronoamperometry/chronocoulometry, and chronopotentiometry. The current-diffusion coefficient relationships that are applicable for each of these techniques are given below [28].
Interfacial Catalysis at Oil/Water Interfaces
Published in Alexander G. Vdlkdv, Interfacial Catalysis, 2002
Potential-step chronoamperometry is a more convenient and accurate way of determining the rate of chemical reactions than cyclic voltammetry. The current responses for the transfer of FRTR +shown in Figure 3 were analyzed quantitatively. The analysis of current -time curve for the ErCi mechanism is simplified when we examine the ratio of the current at tr in the reverse step to that at tr-τ in the forward step, where τ is the time of the potential reversal, as a function of tr-τ/τ[43]. The ratio for the ErCi mechanism is given by [43]
Electrochemical recovery of hydrogen and elemental sulfur from hydrogen sulfide gas by two-cell system
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
J. Narendranath, J. Manokaran, S. Shanmuga Sundar, R. Muruganantham, Ahmed Al Shoaibi, C. Srinivasakannan, N. Balasubramanian
The cyclic voltammetry and electrolysis were carried out using CH instrument (Model CHI660D) workstation. Graphite electrode (geometric area = 1 cm2) was used as both anode and cathode. Calomel (Hg/HgO) electrode was used as the reference electrode. High purity hydrogen sulfide (H2S) was obtained from CHEMIX specialty gas equipment’s. Electrolytes of different equimolar solutions containing NaOH and NaHS (1:1; 2:2; 3:3; 4:4M) were used to conduct the experiment. The solutions used in these experiments were prepared from deionized water and reagent-grade materials. The glass electrolytic cell, consisting of two compartments separated by an ion-selective Nafion 117 membrane, was used to carry out the electrolysis. The cyclic voltammetry, chronoamperometry, and electrolysis were carried out using equimolar solution of NaOH + NaHS as anolyte and NaOH (1M) as catholyte at different pH (9–13) and temperatures (40°C, 60°C, and 80°C). The cyclic voltammetry and electrolysis studies were performed by scanning the potential from −1.5 to +1.5 V at a scan rate of 50 mV s−1. The X-ray diffraction (XRD) measurements were carried out using Xpert-Pro-PAN Analytical Instrument, using the CuKα radiation (λ = 1.540598 Å). The surface morphology of the synthesized samples at microscale was studied using high-resolution scanning electron microscope (HRSEM; Carl Zeiss MA15/EV018) with energy dispersive x-ray (EDAX) analysis using Oxford Instruments Nanoanalyses INCA Energy 250.
Electrochemical characterization and surface morphology techniques for corrosion inhibition—a review
Published in Chemical Engineering Communications, 2023
Shveta Sharma, Richika Ganjoo, Abhinay Thakur, Ashish Kumar
Potentiostat/galvanostat (Figure 4) is very useful in electrochemical measurements and is an effective tool for the detailed knowledge of reaction kinetics, fundamental research, and corrosion. A three-electrode set-up is used for calculating, that are working electrode, reference, and counter electrode respectively (Zhang et al. 2009; Pardo et al. 2010; Zhang et al. 2016). The reaction generally occurs at working electrode and electrolyte surface, and both current and potential should be considered. To study this, suppose potential is applied to working electrode by employing reference electrode, after that current generated has to be measured. If reference electrode is utilized for calculating current, its potential will change and it will not be a reference electrode now, therefore a third electrode (counter) is employed. While in two electrode system exact value of potential cannot be measured. Further the Electrochemical workstation provides various techniques like cyclic voltammetry, linear sweep voltammetry, potentiodynamic polarization, chronoamperometry, impedance spectroscopy, etc.
Doped antimony chalcogenide semiconductor thin films fabrication by physical vapour deposition: elucidation of optoelectronic and electrochemical features
Published in Canadian Metallurgical Quarterly, 2022
Javeria Anwar, Khuram Shahzad Ahmad, Shaan Bibi Jaffri, Manzar Sohail
X-ray diffraction (XRD) analysis was done by XRD (Bruker AXS D-8, Shimadzu, Japan) using Cu-Kα radiations. Vibrational attribution was done via a Fourier Transformer Infra-Red (FT-IR) spectrophotometer (8400, Shimadzu, Japan) using KBr palletisation in the range of 400–4000 cm−1. Optical and morphological analyses were done via a UV-Visible (UV-Vis) spectrophotometer (1602, Biomedical services, Spain) and scanning electron microscopy (SEM) (SEM SS-550 Superscan, Shimadzu, Japan), respectively. Thin-film composition and thickness were analysed by Rutherford backscattering (RBS) spectrometry (3206, Delaware, U.S.A). The parameters adopted for RBS characterisation are shown in Table 2. Photo-electrochemistry of the doped chalcogenide films was studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) using 0.1 mol L−1 KNa(C4H4O6) as a supporting electrolyte.