Codeposition of antimony and tin from acidic chloride and chloride-sulfate baths was investigated. The calculations of distribution of species showed domination of neutral SnCl2 and anionic SbCl4 – complexes in chloride solution, while in the presence of sulfate ions neutral SnSO4 and cationic SbCl2+ complexes were found. Cyclic voltammetry, anodic stripping analysis and potentiostatic measurements showed that antimony deposited favorably and the reaction run under limiting control. Analysis of chronoamperometric curves suggested instantaneous nucleation of the solid phase in the chloride bath, but progressive model was more probable in the presence of sulfate ions.
The paper presents the results of investigation on a prototype sensor for measurement of benzaldehyde in air. Sensitivity and limit of quantification of the sensor were determined for different internal electrolytes using square wave voltammetry (SWV) as the detection technique. The working and counter electrodes were made of platinum. Ionic liquids 1-hexyl, 3-methylimidazolium chloride, 1-hexyl, 3-methylimidazolium bis (trifluoro-methanesulfonyl) imide and 1-butyl, 3-methylimidazolium tricyanomethan constituted the internal electrolyte. A polydimethylsiloxane (PDMS) membrane separated the gaseous medium from the electrolyte.
In this study, molten salt electrorefining was used to recover indium metal from In-Sn crude metal sourced from indium tin oxide (ITO) scrap. The electrolyte used was a mixture of eutectic LiF-KF salt and InF3 initiator, melted and operated at 700°C. Voltammetric analysis was performed to optimize InF3 content in the electrolyte, and cyclic voltammetry (CV) was used to determine the redox potentials of In metal and the electrolyte. The optimum initiator concentration was 7 wt% of InF3, at which the diffusion coefficients were saturated. The reduction potential was controlled by applying constant current densities of 5, 10, and 15 mA/cm2 using chronopotentiometry (CP) techniques. In metal from the In-Sn crude melt was deposited on the cathode surface and was collected in an alumina crucible.
This work presents the studies on the electrochemical process of thin palladium layers formation onto electrodeposited cobalt coatings. The suggested methodology consists of the preparation of thick and smooth cobalt substrate via galvanostatic electrodeposition. Cobalt coatings were prepared under different cathodic current density conditions from acidic bath containing cobalt sulphate and addition of boric acid. Obtained cobalt layers were analyzed by x-ray diffraction to determine their phase composition. Freshly prepared cobalt coatings were modificated by the galvanic displacement method in PdCl2 solution, to obtain smooth and compact Pd layer. The comparison of electrocatalytic properties of Co coatings with Co/Pd ones enabled to determine the influence of Palladium presence in cathodic deposits on the hydrogen evolution process.
This paper presents a voltammetric segmented voltage sweep mode that can be used to identify and measure heavy metals' concentrations. The proposed sweep mode covers a set of voltage ranges that are centered around the redox potentials of the metals that are under analysis. The heavy metal measurement system can take advantage of the historical database of measurements to identify the metals with higher concentrations in a given geographical area, and perform a segmented sweep around predefined voltage ranges or, alternatively, the system can perform a fast linear voltage sweep to identify the voltammetric current peaks and then perform a segmented voltage sweep around the set of voltages that are associated with the voltammetric current peaks. The paper also includes the presentation of two auto-calibration modes that can be used to improve system's reliability and proposes the usage of a Gaussian curve fitting of voltammetric data to identify heavy metals and to evaluate their concentrations. Several simulation and experimental results, that validate the theoretical expectations, are also presented in the paper.
Electrocatalytic gas sensors belong to the family of electrochemical solid state sensors. Their responses are acquired in the form of I-V plots as a result of application of cyclic voltammetry technique. In order to obtain information about the type of measured gas the multivariate data analysis and pattern classification techniques can be employed. However, there is a lack of information in literature about application of such techniques in case of standalone chemical sensors which are able to recognize more than one volatile compound. In this article we present the results of application of these techniques to the determination from a single electrocatalytic gas sensor of single concentrations of nitrogen dioxide, ammonia, sulfur dioxide and hydrogen sulfide. Two types of classifiers were evaluated, i.e. linear Partial Least Squares Discriminant Analysis (PLS-DA) and nonlinear Support Vector Machine (SVM). The efficiency of using PLS-DA and SVM methods are shown on both the raw voltammetric sensor responses and pre-processed responses using normalization and auto-scaling
Carbon paste electrode (CPE) was modified with F-300 commercial activated carbon or Norit SX- 2 powdered activated carbon. CPEs were prepared for detection of 2,4-dichlorophenoxyacetic acid (2,4-D), 2,6-dichlorophenoxyacetic acid (2,6-D) and 2,4,6-trichlorophenoxyacetic acid (2,4,6-T). The electrochemical behavior of these materials was investigated employing cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modifier was found to enhance the electroactive surface area and the peak current in comparison to the bare (unmodified) carbon paste electrode. The intensity of the signal increased with the increase in adsorption ability of the modifiers. Compared to the unmodified electrode, all the new paste electrodes showed a much greater sensitivity for detection of chlorinated phenoxyacetic acids in water samples.
The microstructure and corrosion properties of spark plasma sintered yttria dispersed and yttria free duplex and ferritic stainless samples were studied. Spark plasma sintering (SPS) was carried out at 1000°C by applying 50 MPa pressure with holding time of 5 minutes. Linear sweep voltammetry (LSV) tests were employed to evaluate pitting corrosion resistance of the samples. Corrosion studies were carried out in 0.5, 1 and 2 M concentration of NaCl and H2SO4 solutions at different quiet time of 2, 4, 6, 8 and 10 seconds. Yttria dispersed stainless steel samples show more resistance to corrosion than yttria free stainless steel samples. Pitting potential decreases with increase in reaction time from 2 to 10 seconds. Similarly, as concentration of NaCl and H2SO4 increases from 0.5 M to 2 M the corrosion resistance decrements due to the availability of more Cl¯ and SO4 2¯ ions at higher concentration.