Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride–Urea Deep Eutectic Solvents

Understanding electrocatalytic mechanisms and ultra-trace uranyl detection with Pd nanoparticles electrodeposited in deep eutectic solvents

This research paper investigates the electrocatalytic mechanisms and ultra-trace detection abilities of uranyl ions (UO22+) using palladium nanoparticles (PdNPs) electrodeposited in deep eutectic solvents (DESs). The unique properties of DESs, such as their adjustable viscosity and ionic conductivity, offer an advantageous and environmentally friendly medium for Pd nanoparticle electrodeposition, resulting in highly active and stable electrocatalysts. Various characterization techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), were used to examine the morphology, size distribution, and crystallographic structure of the Pd nanoparticles. Electrochemical tests revealed that the Pd-modified electrodes show exceptional electrocatalytic activity and current sensitivity towards uranyl ions, with detection limits as low as 3.4 nM. Density functional theory (DFT) calculations were conducted to elucidate the mechanism of the electrocatalytic reduction of UO22+ by the PdNPs, providing a plausible explanation for the high sensitivity of PdNPs in detecting uranyl ions based on the calculated structural parameters and reaction energetics. This study underscores the potential of Pd nanoparticles electrodeposited in DESs as a promising method for sensitive uranyl ion detection, contributing to advancements in environmental monitoring and nuclear safety.

Electrodeposition of Polyporous Sn-Ni Coating in Deep Eutectic Solvents for Removing Organic Dyes

Materials with a high specific surface area including a porous structure have been widely researched due to the applicability in the adsorption of various organic dyes. However, further application of porous materials is limited by the complicated and expensive preparation process. Herein, a Sn-Ni coating with a polyporous structure is successfully prepared via a simple and high-efficiency electrodeposition approach in deep eutectic solvents (DESs). The prepared Sn-Ni coating exhibits a uniform polyporous structure with a diameter of 15 μm. Furthermore, the coating shows excellent adsorption capacity in the removal of acid grain black organic dyestuff. With the rise of preparation temperature from 85 to 105 °C, the electrochemical active surface area and the ratio of nickel increase, which further enhance dye adsorption capacity.

Morphology and Structure of Electrolytically Synthesized Tin Dendritic Nanostructures

The formation of tin dendritic nanostructures by electrolysis from the alkaline electrolyte has been investigated. Morphology and structure of Sn dendrites produced applying both potentiostatic and galvanostatic regimes of the electrolysis are characterized by SEM and XRD, respectively. Depending on the applied cathodic potentials, three types of Sn dendrites were obtained: (a) needle-like and spear-like, (b) fern-like, and (c) stem-like dendrites. The very branchy dendrites with branches of the prismatic shape obtained by the galvanostatic regime of electrolysis represented a novel type of Sn dendrites, not previously reported in the literature. To explain the formation of various dendritic forms, correlation with the polarization characteristics for this electrodeposition system is considered. The needle-like and the spear-like dendrites represented monocrystals of (200),(400) preferred orientation, the fern-like dendrites exhibited the predominant (220),(440) preferred orientation, while in the stem-like particles Sn crystallites were oriented to a greater extent in the (440) crystal plane than in other planes. The galvanostatically synthesized Sn particles possessed the strong (200),(400) preferred orientation. The strong influence of parameters and regimes of electrodeposition on structural characteristics of Sn dendrites is explained by the fundamental laws of electrocrystallization taking into consideration the concept of slow-growing and fast-growing crystal planes.

Tin Whiskers' Behavior under Stress Load and the Mitigation Method for Immersion Tin Surface Finish

Since the use of the most stable Pb-based materials in the electronic industry has been banned due to human health concerns, numerous research studies have focused on Pb-free materials such as pure tin and its alloys for electronic applications. Pure tin, however, suffers from tin whiskers' formation, which tends to endanger the efficiency of electronic circuits, and even worse, may cause short circuits to the electronic components. This research aims to investigate the effects of stress on tin whiskers' formation and growth and the mitigation method for the immersion of the tin surface's finish deposited on a copper substrate. The coated surface was subjected to external stress by micro-hardness indenters with a 2N load in order to simulate external stress applied to the coating layer, prior to storage in the humidity chamber with environmental conditions of 30 °C/60% RH up to 52 weeks. A nickel underlayer was deposited between the tin surface finish and copper substrate to mitigate the formation and growth of tin whiskers. FESEM was used to observe the whiskers and EDX was used for measuring the chemical composition of the surface finish, tin whiskers, and oxides formed after a certain period of storage. An image analyzer was used to measure the whiskers' length using the JEDEC Standard (JESD22-A121A). The results showed that the tin whiskers increased directly proportional to the storage time, and they formed and grew longer on the thicker tin coating (2.3 μm) than the thin coating (1.5 μm). This is due to greater internal stress being generated by the thicker intermetallic compounds identified as the Cu₅Sn₆ phase, formed on a thicker tin coating. In addition, the formation and growth of CuO flowers on the 1.5 μm-thick tin coating suppressed the growth of tin whiskers. However, the addition of external stress by an indentation on the tin coating surface showed that the tin whiskers' growth discontinued after week 4 in the indented area. Instead, the whiskers that formed were greater and longer at a distance farther from the indented area due to Sn atom migration from a high stress concentration to a lower stress concentration. Nonetheless, the length of the whisker for the indented surface was shorter than the non-indented surface because the whiskers' growth was suppressed by the formation of CuO flowers. On the other hand, a nickel underlayer successfully mitigated the formation of tin whiskers upon the immersion of a tin surface finish.

Influence of Double-Pulse Electrodeposition Parameters on the Performance of Nickel/Nanodiamond Composite Coatings

In this study, using 45# carbon steel as the substrate, a first experimental analysis was carried out on the polarisation behaviour of different component wattage plating solutions in order to determine the reasonable content of nanodiamond particles in a nickel/nanodiamond composite plating solution. Secondly, the effect of double-pulse forward and reverse duty cycle and reverse working time on the performance of nickel/nanodiamond composite plating was then investigated by testing the thickness, hardness and surface roughness of the composite plating and observing the surface micromorphology. The experimental results show that, when the content of nanodiamond particles in the plating solution is 5 g/L, the anti-pulse working time, forward and reverse pulse duty cycle of the double-pulse plating parameters are 20 ms, 0.3 and 0.2, respectively, and the composite plating layer prepared by double pulse has good comprehensive performance. This research work provides technical support for the optimisation of process parameters for the preparation of nickel/nanodiamond composite coatings by double-pulse electrodeposition.

Treatment of copper converter slag with deep eutectic solvent as green chemical

Industrial copper slag is among the most important wastes to be evaluated in terms of containing valuable metals and the amount of waste approaching 30 million tons per year. Therefore, in this study, it was aimed to propose a feasible route for copper and zinc recovery from copper converter slag (CCS) by using choline chloride (ChCl) based deep eutectic solvent which is applied on this type of slag for the first time. During the leaching experiments with the pure ChCl-2urea mixture, temperature (25-95 °C), leaching duration (2-72 h), and pulp density (1/10-1/40 g/mL) were selected as the parameters to be investigated for Cu and Zn extraction. After the experimental results, the optimized conditions for the ChCl-2urea leaching process, which gave 89.9% Cu and 65.3% Zn extraction was found at 48 h, 95 °C, 1/20 g/mL pulp density with 600 rpm stirring speed. It is noted that the iron dissolution ratio is very low (max. 4.7%) under the selected conditions. At the end of the iron cementation stage, the total recovery efficiency as a pure metallic copper was 63%. The calculated activation energy for the dissolution of the copper and zinc from CCS is 8.86 kJ mol^-1 and 14.48 kJ mol^-1, respectively.