Polyaniline-functionalized TiO2–C supported Pt catalyst for methanol electro-oxidation

Abstract

The hybrid support titania–carbon black (TiO2–C) is used as catalyst support and functionalized by polyaniline (PANI) to further improve the electro-catalytic activity and stability of platinum/titania–carbon black (Pt/TiO2–C) for methanol electro-oxidation for the first time. Pt nanoparticles have been successfully assembled on PANI-functionalized TiO2–C by chemical reduction method in aqueous solutions. PANI may act as a binder to fix the Pt nanoparticles on the TiO2–C support. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. It is observed that with the PANI functionalization, the Pt nanoparticles are smaller in size and more uniformly dispersed on the surface of TiO2–C than those of Pt/TiO2–C. Electrochemical measurements show that the electro-catalytic activity and stability of the novel platinum–polyaniline/titania–carbon black (Pt–PANI/TiO2–C) catalyst are really improved, compared to the Pt/TiO2–C catalyst. The significantly enhanced electro-catalytic activity and stability of Pt–PANI/TiO2–C are mainly ascribed to: (1) the bridging position of PANI between Pt and TiO2–C with the forming of Pt–N bonding; (2) highly dispersed Pt nanoparticles with narrowly distributed particle sizes. These studies indicate that the Pt–PANI/TiO2–C catalyst will become a new type of catalyst for methanol electro-oxidation and may be a promising electrode material for direct methanol fuel cell (DMFC).