Evaluation of the Electrochromic Response of Polypyrrole in the Presence of CO2 in the Solution

The indium tin oxide (ITO)-coated glass was used as a working electrode for electrochemical deposition of conducting polymer polypyrrole (Ppy). Before polymerization, the electrode surface was additionally modified with triethoxymethylsilane (TEMS) to provide better adhesion of polypyrrole to the surface of ITO. The polymerization of Ppy was performed electrochemically, regarding the previous studies. The ionic strength of the solution was supported by LiClO4. Since the dissolved CO2 in the solution forms weak acid and, thus, the pH of a solution can be slightly changed, the electrochromic response to the pH changes was evaluated. Britton–Robinson buffer (BRB) was used as the model system for an evaluation of the electrochromic response of polypyrrole at different pH values and concentrations of NaHCO3, which was a source of CO2 in the solution. For the evaluation of the electrochromic response in the presence of CO2, the double potential step chronoamperometry method was applied and UV-Vis absorption spectra were registered. To gain insight into the charge transfer phenomenon in more detail, the cyclic voltammetry experiments at different glass/ITO(TEMS)/Ppy electrode potential sweep rates were performed.

Investigation of molecular partitioning between non polar oil droplets and aqueous solution using double potential step chronoamperometry

Factors affecting partitioning of an electrogenerated species, Br2 from Br−, into non-polar oil microdroplets at the oil–water–solid interface are investigated using double potential step chronoamperometry.

Voltammetric Determination of Homocysteine Using Multiwall Carbon Nanotube Paste Electrode in the Presence of Chlorpromazine as a Mediator

We propose chlorpromazine (CHP) as a new mediator for the rapid, sensitive, and highly selective voltammetric determination of homocysteine (Hcy) using multiwall carbon nanotube paste electrode (MWCNTPE). The experimental results showed that the carbon nanotube paste electrode has a highly electrocatalytic activity for the oxidation of Hcy in the presence of CHP as a mediator. Cyclic voltammetry, double potential step chronoamperometry, and square wave voltammetry (SWV) are used to investigate the suitability of CHP at the surface of MWCNTPE as a mediator for the electrocatalytic oxidation of Hcy in aqueous solutions. The kinetic parameters of the system, including electron transfer coefficient, and catalytic rate constant were also determined using the electrochemical approaches. In addition, SWV was used for quantitative analysis. SWV showed wide linear dynamic range (0.1–210.0 μM Hcy) with a detection limit of 0.08 μM Hcy. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of Hcy in real samples.