Electrodeposition of manganese (Mn) in butylmethylpyrrolidinium bis(trifluoromethylsulfony)imide (BMP–NTf
2) ionic liquid is demonstrated in this study. Crystal structures and surface morphologies of ...the Mn films deposited at various potentials (from −1.8
V to −2.2
V) and temperatures (from 50
°C to 110
°C) were examined with an X-ray diffractometer (XRD) and a scanning electron microscope (SEM), respectively. Experimental results indicate that the deposited Mn films were amorphous in nature; however, their morphologies strongly depended on the deposition conditions. After being anodized in Na
2SO
4 solution, the deposited Mn was transformed to Mn oxide. Electrochemical properties of the Mn oxides were evaluated using cyclic voltammetry (CV). It was confirmed that the different Mn deposition conditions caused the variations in pseudocapacitive performance of the oxide electrodes. The oxide (∼0.1
mg) anodized from the Mn deposited at −1.8
V and 50
°C had the highest specific capacitance of 402
F/g measured at a CV scan rate of 5
mV/s. Its capacitance retained ratio after 500 CV testing cycles was as high as 94%.
Manganese (Mn) oxide was prepared by anodizing metallic Mn film that was electrodeposited in
n-butylmethylpyrrolidinium bis(trifluoromethylsulfony)imide (BMP–NTf
2) ionic liquid. Different ...anodization courses, namely potentiostatic and cyclic voltammetric methods, led to variations in physical and chemical characteristics of the Mn oxides, and therefore in their pseudocapacitive performance. Evolution of the microstructure, residual weight, and chemical state of the Mn oxides with the charge–discharge cycling number was studied using a scanning electron microscope (SEM), an atomic absorption spectroscope, and an X-ray photoelectron spectroscope, respectively. The analytical results indicate that the electrochemical stability of Mn oxide is mainly determined by its microstructure; the more fibrous (or porous) oxide had a greater durability against cyclic charge–discharge. Moreover, the chemically hydrous state was found to be the most crucial factor that governed the mass specific capacitance of Mn oxide.
The voltammetric behavior of
N-butyl-
N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid (BMP-TFSI) containing Cu(I), Mn(II), or mixtures of Cu(I) and Mn(II) as well as the ...electrodeposition of copper–manganese alloy coatings (Cu–Mn alloy coatings) was studied at 323
K. The Cu(I) and Mn(II) species required to prepare these coatings were introduced into the BMP-TFSI by anodic dissolution of the relevant metallic electrodes. Electrodeposits of Cu, Mn, and Cu–Mn with various contents of Mn can be obtained by controlled-potential electrolysis. It was found that the compositions and surface morphology of the electrodeposited Cu–Mn alloy coatings depend on the deposition potentials and the concentration ratio of Cu(I)/Mn(II) in BMP-TFSI. The Cu–Mn alloy coatings obtained in this study were compact and adherent. They did not show any significant X-ray diffraction signal that could be assigned to the crystalline structures of Cu, Mn, or Cu–Mn alloys. In the aqueous solution containing 0.1
M NaCl, the Cu–Mn alloy coatings demonstrated passive behavior—no continuous oxidation was observed. However, a significant oxidation current was observed at the electrodes deposited with Cu or Mn.
The electrochemistry of manganese was investigated at solid disk electrodes in the hydrophobic room-temperature ionic liquid butylmethylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BuMePy-TFSI) ...by using staircase cyclic voltammetry and chronoamperometry. The Mn(II) species was introduced into the ionic liquid by anodic dissolution of the metallic manganese electrode. The reduction of Mn(II) ions at tungsten and platinum electrodes accompanies with nucleation mechanism and the coupled oxidation wave encounters kinetic hindrance that results in incomplete reoxidation of Mn electrodeposits. The density and absolute viscosity of BuMePy-TFSI were measured over a temperature range from 301.0 to 348.0
K. A polynomial equation describing the temperature dependence of the density is presented. The viscosity exhibits the Arrhenius temperature dependence and the relevant equation is provided. The manganese coatings were prepared by electrodeposition at several substrates. The surface morphology and X-ray diffraction patterns of these deposits were studied by scanning electron microscopy and powder X-ray diffraction spectroscopy, respectively. The as-electrodeposited manganese coatings were amorphous; however, α-phase manganese was observed after the deposits were annealed under 723
K for 1 day.
► Na-doped vanadium oxide is successfully prepared by an electrodeposition technique. ► Microstructure and Na content of the oxide are controlled by deposition potential. ► A lower deposition ...potential leads to a higher porosity of the prepared oxide. ► Na doping significantly increases the oxide capacitance. ► The nanostructured Na-doped oxide shows an ideal supercapacitor performance.
Vanadium-based oxides are prepared on graphite substrates by an anodic deposition technique. The plating bath is 0.2M VOSO4 solution with NaCH3COO addition. A scanning electron microscope and an X-ray diffractometer are used to characterize the deposits; the analyses indicate that the porous Na-doped V2O5 electrodes with a nano-crystalline nature are obtained. Supercapacitor properties of the oxide electrodes are studied using cyclic voltammetry in KCl aqueous electrolyte. The data show that the deposited oxides can exhibit ideal capacitive behavior over a potential range of 1V; the optimum specific capacitance is ∼180F/g. A lower deposition potential leads to a higher porosity of the oxide, resulting in a better high-rate supercapacitor performance of the electrode.
An Al coating film, electrodeposited on a Mg alloy from aluminum chloride–1-ethyl-3-methylimidazolium chloride (AlCl
3–EMIC) ionic liquid, effectively prevents the substrate from rapid corrosion in a ...hostile environment. The thickness of the Al film can be easily determined by controlling the total cathodic charge applied, because the current efficiency of the electrodeposition reaction is close to 100%. Heat treatment at 450
°C under an argon atmosphere for 10
min causes an inter-diffusion at the Al/Mg interface, optimizing the protective performance of the coating film. Prolonging heating leads to a Mg
17Al
12 intermetallic phase and a Mg solid solution phase to be formed at the expense of the deposited Al film. This phase transformation gives rise to a degradation in the corrosion resistance of the Al-coated sample.
Extraction of Cu(II) from neutral aqueous solutions with the hydrophobic room-temperature ionic liquid (IL)
N-butyl-
N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BMP-TFSI) in the ...presence of the pyridine-based ionophore
N
1,
N
1,
N
4,
N
4-tetrakis(2-(pyridin-2-yl)ethyl)butane-1,4-diamine (C
4N
2Py
4) is demonstrated in this study. Although the distribution coefficients,
D
M, of Cu(II) extraction depend on the concentration of Cu(II) in aqueous solutions, all values were higher than 200, indicating extremely high extraction efficiency. Based on spectrophotometric, electrochemical, and X-ray crystallography studies, the coordination number of the C
4N
2Py
4-coordinated Cu(II) ions was determined as 2. The voltammetric behavior of Cu(I), Cu(II), and their C
4N
2Py
4 complex ions were also studied. The recovery of Cu from the IL was conducted by washing the IL phase containing the extracted Cu(II) complex with an acidic aqueous phase or by controlled-potential electrolysis. The IL containing C
4N
2Py
4 was employed for two complete rounds and a decrease in extraction efficiency was only observed when higher concentration of Cu(II) was used.
