Conducting polymer based mesoporous Pt films by using lyotropic liquid crystalline template

Abstract

Polyaniline (PANI) supported platinum (Pt) composite has been proven to exhibit enhanced properties especially in the catalysis of direct methanol fuel cell. To investigate the effects of synthesis method on the properties of the composite, lyotropic liquid crystalline (LLC) template was studied in this experiment. LLC template is a self-assembly soft template, which is widely used in polymer film and metal film synthesis. In this project, Brij 56 was used to form the LLC template for both PANI and Pt. The primary mesoporous PANI films and secondary mesoporous Pt film were electrodeposited onto Indium Tin Oxide (ITO) glass by potentiostatic method and cyclic voltammetry (CV) method. In the physical characterizations, low-angle X-ray diffraction (XRD) and wide-angle XRD had identified the mesoporous structure and composition of the Pt/PANI composite film; while well dispersion of regular spherical Pt particles on the mesoporous PANI support was observed in scanning electron microscope (SEM), indicating high efficiency of the LLC. From the catalytic characterization in methanol oxidation, it was found that Pt-LLC/PANI-LLC composite film produced did not display satisfactory catalytic property, probably due to insufficient Pt catalyst deposited. The amount of Pt deposited onto PANI support was restricted by the weak adhering power of PANI support on the ITO electrode. The investigated synthesis method using LLC template was proven to be a promising way to obtain orderly structured mesoporous film, though much improvement could be done to enhance its catalytic properties. Further work could investigate the properties of Pt-LLC/PANI-LLC composite film electrodeposited on Pt film, carbon or stainless steel electrode, as they provide stronger surface adherence.