Study On Electrochemical Synthesis Of Functional Materials Based On Polyaniline And Its Derivative And Their Applications

Organic conductive polymers, on account of their excellent physical and chemical properties, are promising in many fields such as electrochemical catalysis, electrochemical capacitor, chemical biosensor and so on. Among conductive polymers, polyaniline (PANI) has attracted considerable interesting due to its availability, simple synthesis, high conductivity and stability. In recent years, with the rapid development of nanotechnology and composite materials, metal or metal oxide modified polyaniline and its derivative nanocomposite film with better functional properties have been synthesized. Additionally, some measures have been taken in recent years in order to overcome the disadvantages of inorganic acid doped polyaniline which is insoluble in water and organic solvent, has no excellent resistance to corrosion, has no conductivity and electrochemical activity in neutral medium, is unstable at high temperature. In this paper, Platinum modified polyaniline-metal oxide nanocomposite film,Platinum modified poly(-o-toluidine) nanocomposite film and micro-fibrous polyaniline doped P-Toluenesulfnic acid have been synthesized by pulse potentiostatic method(PPM) and pulse galvanostatic method(PGM), pulse galvanostatic method and cyclic voltammetry method(CVM), pulse galvanostatic method, individually. The applications of platinum modified polyaniline-metal oxide nanocomposite film, platinum modified poly(-o-toluidine) nanocomposite film in electrochemical catalysis and micro-fibrous polyaniline doped P-Toluenesulfnic acid in supercapacitor were investigated. The main progresses are presented as follows:1. Polyaniline-tungsten trioxide(PANI-WO3) composite film was synthesized on the surface of titanium electrode by pulse potentiostatic method. Scanning electron microscope image shows that tungsten trioxide microparticles with a diameter of about 100~150 nm dispersed in nano-fibrous polyaniline and the morphology of polyaniline shows no apparent variation due to WO3 insertion. PANI-WO3 film exhibits good electrochemical activity and has smaller electrochemical impedance than polyaniline film. Pt/PANI-WO3 film electrode presents better electrocatalytic activity for formaldehyde oxidation in contrast to Pt/PANI film electrode. Electrocatalytic activity of Pt/PANI-WO3 film electrode for formaldehyde oxidation is 2~3 times as high as that of Pt/PANI film electrode under the condition of the same film thickness and Pt loading. 2. Platinum microparticles modified poly(-o-toluidine) (POT) composite film was prepared on stainless steel(SS) substrate by a two-step method. The electrochemical property of Pt/POT/SS electrode was studied by cyclic voltammetry in 0.5 mol L-1 H2SO4 solution. The result indicates that Pt microparticles can markedly increase the conductivity of POT while Pt microparticles'activity is sustained. Meanwhile, the electrocatalytic property of the Pt/POT/SS electrode for methanol electrooxidation was investigated by cyclic voltammetry in 0.5 mol L-1 H2SO4+2.0 mol L-1 CH3OH solution. The results show that the Pt/POT/SS electrode has excellent electrocatalytic activity and good stability for methanol electrooxidation, which is attributed to the synergism between POT film and Pt microparticles. Additionally, the effects of anodic charge for depositing POT film, pulse current density for depositing Pt microparticles and Pt loading on methanol electrooxidation were also investigated in detail on this paper.3. Micro-fibrous polyaniline doped P-Toluenesulfnic acid(PANI-TSA) film was synthesized by PGM. The scanning electron microscopy (SEM) result shows that the micro-fibrous PANI doped TSA has a length of 1~2μm micrometers and a diameter of about 150 nm. PANI-TSA film shows good electrochemical activity and excellent supercapacitor when it was prepared under the condition of pulse period of 30 ms: 70 ms, mean pulse current density of 0.5 mA cm-2 and concentration ratio above 4 between TSA and aniline. A specific capacitance of 1036 F g-1 can be obstained at discharge current density of 0.5 mA cm-2. PANI-TSA film shows good electrochemical activity at different pH between 0 and 7. And PANI-TSA film shows good thermal stability under 160℃.