Electrodeposition Of Polypyrrole And Its Composite With Manganese Dioxide

Electrodeposition of polypyrrole (PPy) was conducted on carbon cloth through electrochemical polymerization of pyrrole by cyclic voltammetry. Vibrational absorptions and surface morphologies of PPy were investigated by Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopes (SEM). PPy exited as accumulated spheres to form dense polymer membrane. Electrochemical properties and pseudocapacitive properties of PPy were studied by cyclic voltammetry and chronopotentiometry in solutions of 2 mol·L-1 LiCl,2 mol·L-1 NaCl and 2 mol·L-1 KCl, respectively. PPy displayed a specific capacitance of 180 F·g-1. It found that the cation doping/dedoping into/out of PPy were comparatively easier in the solution of LiCl.Carbon cloth was surface modified in a solution of KMnO4 and H2SO4 to afford modified carbon cloth (MC). Surface morphologies and crystalline structure were investigated by SEM and X-Ray Diffraction (XRD). After surface modification, thin graphite sheets were partial exfoliated on carbon cloth and MnO2 particles can be seen on the surface which may be produced by the reduction KMnO4 Electrochemical properties of MC were investigated by cyclic voltammetry. The influence of concentrations of KMnO4 and H2SO4, modification method and time on properties of MC was investigated. It was found that the MC stirred in the solution of 0.25 mol·L-1 KMnO4 and 0.5 mol·L-1 H2SO4 for 13 h demonstrated the best performance.The PPy/MnO2 composite was obtained by electrodeposition of PPy on MC with MnO2 on its surface by cyclic voltammetry. Typical PPy vibrations were detected on FT-IR spetrum of PPy/MnO2 while characteristic diffractions of MnO2 appeared on the XRD patterns of PPy/MnO2. Surface morphologies of the composite were investigated by SEM. PPy/MnO2 composite existed in nanoparticles, indicating that the size of PPy particles were reduced through composition with MnO2 which will be helpful for the polymer to get good contact with electrolyte. The electrochemical properties and pseudocapacitive properties of PPy/MnO2 were studied by cyclic voltammetry and chronopotentiometry in a solution of 2 mol·L-1 LiCl. The results showed that the electrochemical properties and pseudocapacitive properties of PPy/MnO2 were improved through through composition with MnO2 and the PPy/MnO2 composite display a specific capacitance of 383.5 F·g-1.