Effect Of Preparation Process On Electrocatalytic Oxidation Of Methanol Of Pt-Modifified Polyaniline Electrodes

Direct methanol fuel cell (DMFC) has advantages over other fuel cells for the good handleability, easy preparation and storage of methanol. However, catalysts of DMFC, the noble metal platinum, has some shortages, such as its high price, and easily poisoned by some intermediate products during oxidation of methanol, which restrict DMFC's practical application. So it is necessary to develop the new catalysts for electrooxidation of methanol.Polyaniline, one kind of conducting polymers, with porous structure and high surface area, is usually used as matrix to incorporate Pt particles to prepare Pt-modified Polyaniline electrodes (Pt-PANi/Pt). It is proved that Pt-PANi/Pt electrode has a high efficiency in electrooxidation of small molecules such as methanol, ethanol and formic acid, etc. So Pt-PANi/Pt electrode has a great potential to be used as catalyst in the DMFC.In this paper, cyclic voltammetry (CV), scanning electron microcopy (SEM) and electrochemical impedance spectroscopy(EIS), are used to investigate the phenomenon of methanol oxidation on Pt-PANi/Pt electrode and study the effect of preparing process on electrocatalytic properties.The results show that PANi film prepared by cyclic voltammetry in nitric acid, has larger specific surface area than PANi film prepared by cyclic voltammetry in sulfuric acid, nitric acid or perchloric acid. So it is more suitable as the matrix to incorporate Pt catalysts; the electrocatalytic properties of Pt-PANi/Pt electrode can be improved only by increasing thickness of PANi without adding the loading of Pt, when the thickness of PANi is less than 3.2μm; lastly the growth of Pt particles is affected greatly by electrodeposition method. It is found that pulse potentiostatic method is a good method to deposit Pt particles and the electrocatalytic activity of Pt-PANi/Pt can be improved by reducing the pulse lasting time.