Pt-Au/CNT@TiO2 As a High-Performance Anode Catalyst for Direct Methanol Fuel Cells

Multi-walled carbon nanotubes (CNT) modified using TiO2 nanoparticles (CNT@TiO2) were prepared. Then, Pt-Au/CNT@TiO2 catalysts were prepared by a deposition-UV-photoreduction method for direct methanol fuel cells. The physico-chemical properties of the catalysts were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic performance was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The Pt-Au nanoparticles were found to be uniformly deposited onto the CNT@TiO2 support and had diameters of 2-3 nm. Compared with the Pt-Au/CNT catalyst that was made using a general chemical method, Pt-Au/CNT@TiO2 exhibits higher CO-tolerance for the following reasons. Firstly, the strong interaction between the Pt-Au alloy and TiO2 leads to an increase in electron density on the metallic Pt-Au, which transfers electrons to the pi co * orbital of CO and weakens C-O binding while the oxidation overpotential is lowered. Secondly, the high-valence Ti ions dissociate water to form OHad (ad: adsorbed) species, which then reacts with the strongly bound COad on the Pt surface to form CO2.