Search

Abstract: Carbazole was electropolymerized on indium tinoxide (ITO) electrodes in two air- and water-stable room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate (BMI-PF6) and N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide (BMP-TFSI), respectively, using three potentiostatic methods (i.e., cyclic voltammetry, potentiostatic electrolysis, and potentiostatic pulse electrolysis). The polymer films obtained in both ionic liquids (ILs) adhered on the electrode surface well; however, the polycarbazole (PCz) films obtained in the more viscous BMI-PF6 exhibited a denser structure. The PCz films showed electrochromic behavior; deep green was observed in the oxidative state and pale green in the reductive state. Anions or viscosities of the ILs seem to influence the depth of color change. PCz films were also prepared under a normal atmosphere. [Copyright &y& Elsevier]

Abstract Water-insoluble PbSO 4 only slightly dissolved in an amide-type hydrophobic protic ionic liquid (IL); the protonated betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]). However, the paste of [Hbet][TFSA]-PbSO 4 coated on screen-printed carbon electrode (SPCE) could be electrochemically converted to Pb or PbO 2 in aqueous 0.1 M KCl via constant-potential electrolysis for the former and continuous cyclic voltammetry in 0.1 M NaOH for the latter. The formation of PbO 2 , which could be converted to CoO x (containing Co 3 O 4) through galvanic displacement in a Co(NO 3) 2 aqueous solution, was verified with Raman scattering spectroscopy and X-ray photoelectron spectroscopy (XPS); the latter also verified the formation of Co 3 O 4. The CoO x -modified electrode showed activity and high stability towards the oxygen evolution reaction (OER) in alkaline solutions. The approach shown in this study can be further developed as a procedure for extracting Pb metal or preparing CoO x catalysts from wastes, such as the discarded lead-storage batteries. Graphical abstract Unlabelled Image Highlights • A protic hydrophobic amide-type ionic liquid (IL) was mixed with PbSO 4 to be a paste. • The paste can be electrochemically converted to Pb or PbO 2. • PbO 2 can be further converted to Co 3 O 4 via galvanic displacement. • The Co 3 O 4 -modified PbO 2 electrode showed activity to oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Abstract Two electropolymerizable carbazole-functionalized viologen compounds were synthesized and characterized using NMR, ESI-MS, voltammetry, and spectroelectrochemistry. The compounds were electropolymerized onto indium tin oxide electrode and glassy carbon electrode through a radical-induced polymerization triggered by electrochemical oxidation at the carbazole moieties in electrolytes composed of room temperature ionic liquid/organic solvents or NaClO 4 /acetonitrile. It was found that the properties of the electropolymerized polymers were crucially controlled by the chemical structure of the monomer and the electrolyte compositions. The polymer films showed electrochromic behavior, and the color changed from greenish at the potential where carbazole groups were oxidized to violet or colorless at which reduction of viologen groups occurred; violet or colorless depended on which of the two reductive states of the viologen moieties was reached. The polymer films were capable of enhancing the oxidative current of uric acid and ascorbic acid, respectively, in neutral media, which might be due to the concentrating ability of the viologen moieties towards negatively charged species such as ferricyanide ([Fe(CN) 6 ]3−) and ferrocyanide ([Fe(CN) 6 ]2−). Graphical abstract Unlabelled Image Highlights • Carbazole substituted viologen was prepared as electropolymerizable monomers. • Monomers with mono- or di-carbazole groups were prepared. • Single-backbone or two-backbone conducting polymers could be formed. • Not only the monomer structures but the electrolytes control the polymer properties. • The polymers show the electrochromic and anion-adsorptive behavior. [ABSTRACT FROM AUTHOR]

In this study, an ionic liquid-Fe 3 O 4 nanoparticles-graphite composite electrode (IL-Fe 3 O 4 NPs-GP) with high sensitivity was fabricated using easy-to-made materials and convenient techniques. A hydrophobic ionic liquid 1-butyl-1-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)amide (IL BMP-TFSA) was used to substitute paraffin oil that is conventionally used as the organic binder for preparing carbon paste electrodes. Fe 3 O 4 NPs show pseudo-peroxidase activity toward hydrogen peroxide (H 2 O 2 ) that was electrocatalytically reduced at the electrode. This electrode shows the synergistic effect from the combination of IL and Fe 3 O 4 NPs, exhibiting a high sensitivity of 200.7 μA mM −1 cm −2 but a narrower dynamic range of 1–25 μM with a detection limit of 0.5 μM. This electrode also shows good stability and several common interferents show negligible effect on the determination of H 2 O 2 . [ABSTRACT FROM AUTHOR]

Abstract: The voltammetric behavior of Pt(II), Fe(II), and mixtures of Pt(II) and Fe(II) was studied in N-butyl-N-methylpyrrolidinium dicyanamide ionic liquid (BMP-DCA IL), N-butyl-N-methylpyrrolidinium bis((trifluoromethyl)sulfonyl)imide ionic liquid (BMP-TFSI IL), and a mixture of BMP-DCA and BMP-TFSI, respectively. Electrodeposition of PtFe coatings was achieved by controlled-potential electrolysis on tungsten from the aforementioned ILs containing Pt(II) and Fe(II). The Pt(II) species required to prepare these PtFe coatings was introduced into the ILs by addition of PtCl2. In BMP-TFSI, an additional two equivalents of N-butyl-N-methylpyrrolidinium chloride (BMP-Cl) were essential to assist one equivalent of PtCl2 to dissolve. The Fe(II) species was introduced into the ILs by addition of FeCl2 or by anodizing an iron spiral electrode. In BMP-TFSI, additional BMP-Cl had to be added to assist FeCl2 dissolution (FeCl2:BMP-Cl=1:2 (mol:mol)). The PtFe coatings with various atomic ratios of Pt/Fe were studied for their voltammetric behavior towards the oxygen reduction reaction (ORR) in acidic solutions. This study shows that the PtFe alloy coatings with atomic ratios of ∼0.5/0.5 had the highest reductive current density for ORR, better than regular Pt or Pt-electrodeposited electrodes. [ABSTRACT FROM AUTHOR]