Codeposition of Cu-Sn from Ethaline Deep Eutectic Solvent

Design Strategy and Application of Deep Eutectic Solvents for Green Synthesis of Nanomaterials

The first report of deep eutectic solvents (DESs) was released in 2003 and was identified as a new member of ionic liquid (IL), involving innovative chemical and physical characteristics. Using green solvent technology concerning economical, practical, and environmental aspects, DESs open the window for sustainable development of nanomaterial fabrication. The DESs assist in different fabrication processes and design nanostructures with specific morphology and properties by tunable reaction conditions. Using DESs in synthesis reactions can reduce the required high temperature and pressure conditions for decreasing energy consumption and the risk of environmental contamination. This review paper provides the recent applications and advances in the design strategy of DESs for the green synthesis of nanomaterials. The strategy and application of DESs in wet-chemical processes, nanosize reticular material fabrication, electrodeposition/electrochemical synthesis of nanostructures, electroless deposition, DESs based nano-catalytic and nanofluidic systems are discussed and highlighted in this review.

Uncovering biodegradability and biocompatibility of betaine-based deep eutectic systems

Deep eutectic systems (DES) have shown increasing popularity in last decade; however, the number of studies on the potential toxicity towards living organisms remains scarce. These studies are of the utmost importance to infer on the claimed non-toxicity and biocompatibility of DES. Most articles published, at this moment, only evaluate the toxicity towards a cell model or in different strains of bacteria. For this purpose, in this work, the effect of two DES (betaine:sorbitol:water 1:1:3 and betaine:glycerol 1:2) and their individual components were evaluated at different concentrations after administered via intraperitoneal injection in zebrafish (Danio rerio). The total antioxidant capacity, lipoperoxidation, and the activity of various enzymes that work in different antioxidant pathways (superoxide dismutase, glutathione peroxidase, catalase, and glutathione S-transferase) were assessed. The results show no significant toxicity within the tested concentrations: up to 5000 µM and 3000 µM, for the assays using the system betaine:sorbitol:water 1:1:3 and for betaine:glycerol 1:2, respectively. The toxicity of individual components was studied up to 1000 µM. Based on the encouraging results that have been obtained, it is safe to conclude that these two deep eutectic systems can be used as the new class of environmentally friendly solvents.

Assessment of deep eutectic solvents toxicity in zebrafish (Danio rerio)

Deep Eutectic Systems (DES) have emerged as a "green alternative" to organic solvents and have been coined as biocompatible and biodegradable. However, the number of studies concerning the real biodegradability and biocompatibility are scarce. Thus, to study the toxicity of certain DES, two different approaches were used: i) zebrafish exposure via water, where the system (DES) was tested at potentially realistic environmental concentrations and ii) via intraperitoneal injection, where the system was tested in different concentrations, relevant to the pharmaceutical industry. These studies were performed using zebrafish, a standardized animal model often used in biomedicine and toxicological assays. The results show low toxicity according to tested concentrations (up to 73.47 μM), when the system CA:T:W, with a 2:1:3 molar ratio, was tested through exposure via water and also in the intraperitoneal injection tests with concentrations up to 6000 μM. The activity of different enzymes involved in antioxidant pathways (glutathione S-transferase, catalase, glutathione peroxidase), the total antioxidant capacity (TAC) and lipoperoxidation (MDA content) were determined suggesting low toxicity of the tested system (DES). The promising results herein presented show that DES present the potential to be used as the new class of green solvents, not only for use in the pharmaceutical industry, but also in cosmetic and chemical engineering processes without causing negative impact on living organisms.

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

The electrochemical behavior and electrodeposition of Sn were investigated in choline chloride (ChCl)–urea deep eutectic solvents (DESs) containing SnCl2 by cyclic voltammetry (CV) and chronoamperometry techniques. The electrodeposition of Sn(II) was a quasi-reversible, single-step two-electron-transfer process. The average transfer coefficient and diffusion coefficient of 0.2 M Sn(II) in ChCl–urea at 323 K were 0.29 and 1.35 × 10−9 cm2∙s−1. The nucleation overpotential decreased with the increase in temperature and SnCl2 concentration. The results of the chronoamperometry indicated that the Sn deposition on tungsten electrode occurred by three-dimensional instantaneous nucleation and diffusion controlled growth using the Scharifker–Hills model. Scanning electron microscopy (SEM) showed that the morphology of the deposits is uniform, as a dense and compact film prepared by potentiostatic electrolysis on Cu substrate. X-ray diffraction (XRD) analysis revealed that the deposits were pure metallic Sn.

Comparative Study of Ni-Sn Alloys Electrodeposited from Choline Chloride-Based Ionic Liquids in Direct and Pulsed Current

This work presents, for the first time, the electrodeposition of Ni-Sn alloys in pulse current, from deep eutectic solvents (choline chloride: ethylene glycol eutectic mixture). Additionally, in this study, we report a comparison of the electrodeposition methods known as pulse and direct current. The elemental composition of the films, evaluated from EDX, remained almost constant independently on the electrodeposition parameters. The XRD data revealed the presence of the NiSn metastable phase, which has been confirmed by DSC analysis. This phase shows a nanocrystalline structure with crystallite sizes between 12 and 20 nm. The use of pulse current electrodeposition method has led to an improvement of alloys’ mechanical properties. Moreover, by controlling the electrodeposition parameters, we succeeded in tuning the mechanical properties of the coatings prepared through the PC method. We showed that the hardness parameters exhibited by the Ni-Sn alloys are strongly dependent on their crystallite sizes.

Tin, Bismuth, and Tin-Bismuth Alloy Electrodeposition from Chlorometalate Salts in Deep Eutectic Solvents

The electrodeposition of tin, bismuth, and tin-bismuth alloys from SnII and BiIII chlorometalate salts in the choline chloride/ethylene glycol (1:2 molar ratio) deep eutectic solvent was studied on glassy carbon and gold by cyclic voltammetry, rotating disc voltammetry, and chronoamperometry. The SnII-containing electrolyte showed one voltammetric redox process corresponding to SnII/Sn0. The diffusion coefficient of [SnCl3]-, detected as the dominating species by Raman spectroscopy, was determined from Levich and Cottrell analyses. The BiIII-containing electrolyte showed two voltammetric reduction processes, both attributed to BiIII/Bi0. Dimensionless current/time transients revealed that the electrodeposition of both Sn and Bi on glassy carbon proceeded by 3D-progressive nucleation at a low overpotential and changed to instantaneous at higher overpotentials. The nucleation rate of Bi on glassy carbon was considerably smaller than that of Sn. Elemental Sn and Bi were electrodeposited on Au-coated glass slides from their respective salt solutions, as were Sn-Bi alloys from a 2:1 SnII/BiIII solution. The biphasic Sn-Bi alloys changed from a Bi-rich composition to a Sn-rich composition by making the deposition potential more negative.