A review on electrochemical properties of choline chloride based eutectic solvent in mineral processing

Avery

et al. 2021

J. Electrochem. Soc.

The dissolution and deposition behavior of molybdenum in a deep eutectic solvent was examined to assess the possibility of molybdenum electrorefining. When added to the ethaline, MoCl5 exhibited electrochemically irreversible behavior and appeared to be reduced via a two-electron reaction. However, Mo metal deposition was not observed, even after an extended period at high cathodic overpotentials. Deposition of molybdenum from ethaline at 80 °C was enabled by adding fluoride ions to the liquid to alter the speciation of the metal complex. Fluoride changed the electrochemical behavior of Mo in solution determined by cyclic voltammetry. Mo was successfully deposited from ethaline onto a nickel substrate at constant potential in the presence of fluoride ions, as confirmed analytically. The impact of fluoride ions on the anodic dissolution of molybdenum in ethaline was also found to not significantly hinder the dissolution process. Thus, both dissolution and deposition of molybdenum are possible in a DES, opening the way for possible development of a Mo electrorefining process.

Section: Resultsmentioning

confidence: 64%

Mo Deposition and Dissolution in DES with the Use of Fluoride Salts

Avery

et al. 2021

J. Electrochem. Soc.

“…The increased zinc electrodeposition on the annealed substrate as compared to the as-anodized substrate can also be confirmed from Figures S7 and S8 in the Supporting Information. This could indicate a higher nucleation and growth rate on a more conductive substrate since in an ionic liquid electrolyte such as DES, the electrolyte conductivity is not sufficiently high enough that the conductance of substrates has a more noticeable effect on the deposition results. , In Figure c, the surface details of the as-anodized TiO 2 nanotube array present random “pits” that correspond to darker spots in Figure S10a in the Supporting Information. Zinc NHexs are shown to preferentially nucleate in such locations with less-ordered surface features, leading to a less uniform deposition of zinc NHexs on the substrate surface overall.…”

Section: Discussionmentioning

confidence: 99%

Zinc Nanoparticles Electrodeposited on TiO₂Nanotube Arrays Using Deep Eutectic Solvents for Implantable Electrochemical Sensors

Wang

Phelps

Abdolvand

et al. 2023

ACS Appl. Nano Mater.

This work reports on the electrodeposition of zinc on nanoporous metal oxide titania nanotube arrays (TiO2 NTAs) using a zinc-containing deep eutectic solvent (Zn2+–DES). The effects of substrate morphology and crystallinity, deposition temperature, zinc concentration, and deposition time on the morphology and electrochemical properties of the Zn/TiO2 NTAs were investigated. Two-dimensional zinc nanohexagons (NHexs) with a mean diameter of ∼300 nm and a thickness of 10–20 nm were decorated onto the TiO2 NTAs (with a pore diameter of ∼80 nm and a tube length of ∼5 μm) via electrodeposition at −1.6 V using Zn2+–DES. Cyclic voltammetry tests on the Zn2+–DES electrolyte revealed an electrochemical window of ∼3.5 V, and the diffusion coefficient of Zn2+ was found to be 4.29 × 10–10 cm2 s–1 at room temperature and 7.10 × 10–10 cm2 s–1 at 40 °C. Zinc nucleation on TiO2 NTA substrates followed an instantaneous model. Using a higher electrodeposition temperature increased the nucleation and growth rate of zinc NHexs, while annealing TiO2 NTAs was found to improve their uniformity and morphology. During the initial stage of deposition, hexagonal close-packed zinc NHexs were found to preferentially grow on tetragonal anatase TiO2 NTAs. The electrodeposition of zinc resulted in lowering the impedance and improving the overall electrochemical properties of TiO2 NTAs. The Zn/TiO2 NTAs developed in this study offer a promising electrocatalyst material system for implantable electrochemical sensors.

Critical Assessment of the Sustainability of Deep Eutectic Solvents: A Case Study on Six Choline Chloride-Based Mixtures

et al. 2022

An outline of the advantages, in terms of sustainability, of Deep Eutectic Solvents (DESs) is provided, by analyzing some of the most popular DESs, obtained by the combination of choline chloride, as a hydrogen bond acceptor, and six hydrogen bond donors. The analysis is articulated into four main issues related to sustainability, which are recurrently mentioned in the literature, but are often taken for granted without any further critical elaboration, as the prominent green features of DESs: their low toxicity, good biodegradability, renewable sourcing, and low cost. This contribution is intended to provide a more tangible, evidence-based evaluation of the actual green credentials of the considered DESs, to reinforce or question their supposed sustainability, also in mutual comparison with one another.