Electropolymerization And Electrochemical Properties Of Polyaniline/Diamond Composite

The unique electrochemical properties of nanodiamond such as a large working potential window, a low background current and prolonged stability make it attractive for applications as an electrode material. Polyaniline (PANI) was electropolymerized on undoped 100 nm diamond powders by using a cyclic voltammetry (CV) method aiming to improve the conductivity and the electrochemistry of the nanodiamond particles. The effects of the upper potential limits, the scan rate, the concentration of aniline monomer and H₂SO₄ solution were investigated. The means of X-ray diffraction, fourior transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy were adopted for characterizing. Electrochemical properties were investigated by CV and electrochemical impedance spectroscopy (EIS).The results suggested that a upper potential limit higher than 0.9 V was necessary to start the eletropolymerization. Aniline monomer with a concentration of 0.05 mol/L would be degradated but not polymerized on a nanodiamond electrode. The characteristic redox peaks of PANI appeared in the solution with more than 0.1 mol/L aniline concentration. When a concentration ratio of aniline/H₂SO₄ was more than 1:1, the electropolymerization of PANI happened. The prepared PANI was partly crystalline. The characteristic absorption bands of PANI were detected in FTIR spectra and showed slightly red shift. The Granular PANI forming and growing into fibrous associated with the cyclic times. The resulting electrode was electrochemically active in acid medium. The resistance of the nanodiamond electrode was 4.65×10⁵Ωwhile the value of the redulting PANI/diamond electrode decreased to 1.15×10³Î©. Electropolymerized under the upper potential limit of 1.5 V, the capacitance of the resulting electrode in low frequence comes to 101.5μF. The PANI/diamond composite has good stability to withstand 2.2 V potential.