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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]

Electrodeposition of lead (Pb) is important because of the application for energy storage and Pb recovery. Water, however, is not a good solvent because many Pb compounds, such as Pb oxides used in Pb storage batteries, are insoluble. Ionic liquids (ILs), especially for deep eutectic solvents (DESs), have been used for Pb electrodeposition. However, most DESs are water-miscible. Here, a hydrophobic Brønsted acidic amide-type IL, protonated betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]), was used to dissolve PbO and PbO 2 under an ambient air for the voltammetric study and electrodeposition. PbSO 4 was only slightly soluble but extraction of Pb metal was achieved from the PbSO 4 /[Hbet][TFSA] paste. Very smooth, uniform, and crystalline electrodeposits were obtained from the PbO and PbO 2 baths, respectively, regardless of potentiostatic or galvanostatic electrodeposition but dendritic Pb was obtained from DESs. The Pb species in the IL was carefully studied, and the different species might explain why different morphologies of Pb were obtained from this IL and DESs, respectively. This study demonstrates that a protic IL is appropriate to be used as the electrolyte for electrochemically extracting Pb from various water-insoluble Pb compounds. [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]