ABSTRACT
An electrochemical method for loading electroactive materials over the TEM grid is reported. The protocol has been demonstrated using polyaniline as an example. The electroactive polymer was directly deposited over the Au TEM grid, used as working electrode in a 3 electrode electrochemical cell. The undisturbed as-deposited morphologies under the influence of various counter ions and ex situ electrochemical states have been studied and compared. Contrary to behaviour in bulk the individual polyaniline fibre was found thinner at anodic potentials. The movement of counter ions as a function of the electrochemical state of the polymer was studied using STEM-EDX elemental mapping.
ABSTRACT
A specific and efficient hydrogen bonding interaction between cyanide and the HN-H [imidazole] in an aqueous medium has been utilized for the selective recognition of cyanide under physiological conditions. The possibility of utilizing such an interaction for developing any practical device for the specific detection of cyanide in an aqueous environment has not been explored to date. We now report a simple dip and read conductometric sensor for cyanide ions using a tailored electrode in aqueous media. The purpose built reagent, 2-phenyl-1H-anthra-[2,3-d]-immidazole-5,10 dione was immobilized in a polyaniline matrix to fabricate this conductometric device. The homogeneous immobilization of the receptor in polyaniline was confirmed by FT-IR mapping. The proposed transduction mechanism is charge neutralization on the polyaniline moiety, which ultimately inhibits the protonation resulting in a decrease in the conductance of polyaniline. The sensor response was measured in three ranges of cyanide concentration (10(-10) M to 10(-8) M; 10(-8) M to 10(-6) M and 10(-6) M to 10(-3) M). Whereas the device is found insensitive in the first range, it acts as a detector in the second range and as a proportional sensor in the third range. The minimum detection limit of this device was found to be 10 nmol L(-1) (2.6 ppt), which is significantly less than the WHO guideline values. The responses have been investigated under various conditions such as different pH and the electrochemical state of the polymer. The current device has been found to be better close to neutral pH and at a 400 mV vs. Ag/AgCl potential. The reproducibility and repeatability of the sensor was investigated and interference studies were performed.
Subject(s)
Cyanides/analysis , Imidazoles/chemistry , Conductometry , Electrochemical Techniques , Hydrogen Bonding , Molecular StructureABSTRACT
We report an efficient plastic chip electrode (PCE) fabricated from a composite of graphite and poly(methyl methacrylate) by a simple solution casting method and promoted as an economically inexpensive, multipurpose disposable electrode for various applications. The TEM images of the filler (graphite) show that the material consists of single, as well as multi-layers. Thus, the self-standing and arid electrodes prepared were characterized for their material properties such as, microscopy (SEM and AFM), as well as thermal properties (TGA), mechanical (tensile strength) and electrical properties. A set of physical parameters were derived from these characterizations for sustainability of these electrodes in harsh off-laboratory conditions. The utility of these mechanically stable, bulk-conducting and high surface area electrodes were demonstrated in various well understood electrochemical protocols, such as cyclic voltammetry, stripping voltammetry, electropolymerization, electrowinning and amperometric sensing. The voltammetry data were compared with the data recorded on a conventional glassy carbon electrode.
ABSTRACT
A simple and effective method for the management of the passive layer in solid state batteries is reported. The success is achieved using a composite cathode with embedded channels of polyaniline allowing smooth charge transfer across the passive layer. The composite cathode manifested better performance in terms of the cell characteristics and shelf life.
