Synthesis Of Polyaniline/nano-Manganese Dioxide Composite And Applications In Supercapacitors

Manganese dioxide nanoparticles were synthesized by inorganic salt water solution reaction from KMnO4 and MnS04, followed by heating and acidification. Nano-rods were obtained based on transmission electron microscope (TEM) measurement. Characteristic patterns ofα-MnO2 andγ-MnO2 were detected through powder X-ray diffraction (XRD).MnO2 nanoparticles were surface-modified by silane coupling agent---ND42. Characteristic vibrations of both ND42 and MnO2 appeared on FT-IR spectrum of surface-modified particles ND-MnO2.The polyaniline/nano-manganese dioxide composite film (PAn/MnO2) and the polyaniline/modified nano-manganese dioxide composite film (PAn/ND-MnO2) were obtained electrochemically by cyclic voltrammetric (CV) scans in media of 0.5 mol·L-1 H2SO4 containing 0.1 mol·L-1 aniline, respectively. The composite films display characteristic behaviors of PAn in 0.5 mol·L-1 H2SO4 based on cyclic voltramograms. Composite films of cyclic voltrammetry and galvanostatic charge/discharge (CP) showed specific capacitance of PAn/MnO2 and PAn/ND-MnO2 under 3.93 mA·cm-2 in 1.0 mol·L-1 NaNO3 (pH=1), respectively, which were 104.9% and 134.3% than that of similarly prepared PAn. The composite films exhibited nanofibrous structures with thinner coral-rod size than that of PAn in diameter by means of SEM. It indicates that the composite films'higher specific capacitance than PAn is owing to their bigger specific surface area and more micro-channels.Symmetric supercapacitorsⅠandⅡwere constructed by using the composite films as electrodes and 1.0 mol·L-1 NaNO3 (pH=1) as electrolyte, respectively. The CV and CP results show that the supercapacitors display substained stability and perfect coulombic efficiency over 250 cycles.