Tan Wee Tee

CATHODIC ELECTRODEPOSITION OF Cu 4 SnS 4 THIN FILMS FROM ACIDIC SOLUTION

In this work the synthesis of copper tin sulfide thin films by electrodeposition is carried out. The films were deposited onto ITO glass substrates from an aqueous solution bath containing copper sulfate, tin chloride and sodium thiosulfate at pH 1 and room temperature. Prior to the deposition, a cyclic voltammetry experiment was carried out between two potential limits (+1000 to -1000 mV versus Ag/AgCl) to probe the effect of the applied potential and to determine the most likely suitable electrodeposition potential for the deposition of copper tin sulfide. The deposition was attempted at various cathodic potentials such as -400, -600, -800, -1000 mV to determine the optimum deposition potential. The films have been characterized by techniques such as optical absorption, Xray diffraction and atomic force microscopy. The XRD patterns show that the films are polycrystalline with orthorhombic structure. The AFM studies reveal the electrodeposited films were smooth, compact and uniform at deposition potentials of –600 mV versus Ag/AgCl. The direct optical band-gap energy was obtained to be 1.58 eV.

Electrochemical Oxidation of Paracetamol Mediated by MgB2 Microparticles Modified Glassy Carbon Electrode

A MgB2 microparticles modified glassy carbon electrode (MgB2/GCE) was fabricated by adhering microparticles of MgB2 onto the electrode surface of GCE. It was used as a working electrode for the detection of paracetamol in 0.1 M KH2PO4 aqueous solution during cyclic voltammetry. Use of the MgB2/GCE the oxidation process of paracetamol with a current enhancement significantly by about 2.1 times. The detection limit of this modified electrode was found to be 30 μM. The sensitivity under conditions of cyclic voltammetry is significantly dependent on pH, supporting electrolyte, temperature and scan rate. The current enhancement observed in different electrolytic media varied in the following order: KH2PO4 > KCl > K2SO4 > KBr. Interestingly, the oxidation of paracetamol using modified GC electrode remain constant even after 15 cycling. It is therefore evident that the MgB2 modified GC electrode possesses some degree of stability. A slope of 0.52 dependent of scan rate on current indicates that the system undergoes diffusion-controlled process.

Electrochemical detection of DNA hybridization based on bismuth oxide nanoparticles/chitosan-modified electrodes with methylene blue as an electrochemical indicator

The detection of DNA hybridization is of central importance to the diagnostic and treatment of genetic diseases, for the detection of infectious agents, and for reliable forensic analysis [1]. The technique for the detection of DNA hybridization has attracted many attentions. Many methods for detecting hybridization have been developed, including electrochemical, optical, microgravimetric methods and surface plasma resonance. As compared with other detection techniques, the main advantages of electrochemical techniques are their low cost, small size, and convenience for integration and microminaturizaion. Hence, DNA electrochemical biosensors have been rapidly developed recently [2–7].