Electrochemical Preparation of Fe0.5CoNiCuSnx Medium Entropy Alloys and Their Corrosion Properties

The exploration of efficient preparation methods and corrosion-resistant medium entropy alloys (MEAs) has attracted significant attentions in recent years. In this paper, powdery Fe0.5CoNiCuSnx (x=0, 0.05, 0.08, and 0.1) MEAs were prepared by the one-step electrochemical reduction of metal oxides in molten Na2CO3-K2CO3 using a Ni11Fe10Cu oxygen-evolution inert anode. The effects of Sn on the structures, morphologies, and corrosion behaviors of the prepared MEAs were systematically investigated. The electrolytic MEAs exhibited a single face-centered cubic phase at x≤0.05, and the CuSn-rich phase would be segregated in the alloys at 0.08≤x≤0.1. Moreover, increasing Sn reduced the particles size of MEAs, and Sn improved the corrosion resistance of MEAs in 0.5 M H2SO4, 1 M KOH, and 3.5% NaCl solutions. The electrolytic MEA(Sn0.05) exhibited the best corrosion resistance, which had the corrosion current densities of 3.7×10-5 A/cm2 (0.5 M H2SO4), 1.2×10-5 A/cm2 (1 M KOH), and 1.6×10-5 A/cm2 (3.5 wt% NaCl) at room temperature. Overall, this paper not only provides a green approach to preparing Sn-containing MEAs, but also offers an efficient way to control structures and morphologies, thereby improving the corrosion resistance.

Electrochemical Preparation of Nano-Sized Silicon as a Lithium-Ion Battery Anode Material

Highly pure silicon is an important component in photovoltaic applications and has potential in battery technology. In this study, the electrochemical behavior of Si (IV) was discussed in a NaF−LiF−Na2SiO3−SiO2 electrolyte at 750 °C , and lithium-ion battery performance with electrodeposited silicon powder as anode material were investigated. The cyclic voltammograms illustrated that the reduction of Si(IV) on an Ag electrode followed an irreversible two-step, two-electron process: Si(IV) → Si(II) and Si(II) → Si(0). Both reduction steps involved diffusion control, and the diffusion coefficients were 1.18 and 1.22 × 10−6 cm2/s, respectively. Nanoscale spherical silicon was deposited between potentials of −1.0 to −1.6 V (vs. Pt) with support of X-ray diffraction patterns, Raman spectra, and scanning electron microscopy analysis. Combining the fabricated silicon with carbon, a Si@C composite anode material for lithium-ion batteries was prepared, and its specific capacity reached 1260 mAh/g. Notably, a capacity of 200 mAh/g was maintained over 100 cycles.

Polimeryzacja aniliny w środowisku stałego pola magnetycznego

Polyaniline is an example of an electronically conducting polymer. During the oxidation of the polymer, positive charges appear in its structure, which must be compensated for e.g. by the presence of anions in the polymer layer. The form of polyaniline depends on both the degree of oxidation and the degree of protonation of the polymer, i.e. the pH of the solution. Due to the ease of electrochemical preparation of polyaniline, as well as the possibility of full control of the course of the process, the influence of the constant magnetic field (s.p.m.) on the reaction of its preparation was additionally investigated. The cyclic voltammetry (CV) method was used for this purpose. Aniline polymerization processes were carried out on platinum, plate electrodes, not insulated (A) and insulated on two different sides with Teflon, with surfaces directed parallel to the line of force of the s.p.m. (To beat). Research on the electrochemical preparation of polyaniline in s.p.m. allowed to conclude that the following factors affect the magnitude of the current in the tested process: (i) the magnitude of the magnetic induction vector B, (ii) the position of the electrode plane in relation to the direction of the vector B, (iii) the type of electrode (insulated on one side or not). Impact on the impact of s.p.m. the magnetic properties (e.g. paramagnetic, diamagnetic) of the particles participating in the electrochemical reaction, as well as their charge (+/-), also had an effect on the electrochemical polymerization processes. Based on the experimental results, the mechanism of the influence of s.p.m. was proposed. on the tested electrochemical reactions. This mechanism was based, inter alia, on the formation of the magnetohydrodynamic effect (MHD), which causes a change in the speed of transport of the reacting substances to the electrode, the magnetohydrodynamic movement of the electrolyte and the change in the kinetics of electrode processes. For the tested process, changes in the rate constants of electrochemical reactions (ks) as a result of external action of s.p.m. were around 30%.

Preparation of Solutions of Titanium Trichloride-Based Complex Coagulants

One of the largest sources of heavy metal compounds entering the hydrosphere is galvanic production. Despite their high danger, chromium (VI) compounds are widely used in electroplating. Electrolytes based on chromium (VI) compounds are stable at all pH values and, if released into water, pose a serious problem for wastewater treatment plants. The purpose of this study was to assess the possibility of thermal and electrochemical preparation of solutions of complex coagulants-reducing agents based on titanium trichloride for wastewater treatment from chromium (VI) compounds. Findings of research show that the yield of titanium trichloride is practically independent of the production method, however, the process of electrochemical synthesis is much more stable, the reaction mixture is slightly heated, which has a positive effect on the storage time of the obtained reagent solutions. The study proves that in terms of their effectiveness, the samples of the complex coagulant-reducing agent are superior to individual reagents based on iron (II) compounds. Moreover, the use of complex reagents makes it possible to considerably intensify the processes of sedimentation and filtration of the resulting sludge, which allows us to significantly reduce the dimensions of the equipment and increase the economic efficiency of the water purification process as a whole