Effect of structure of carbon nanotubes on electrocatalytic performance of carbon nanotubes supported Pt catalysts

The effect of the tube diameter of the carbon nanotubes (CNTs) as the supporter of Pt catalyst on the electrocatalytic activity of the CNTs supported Pt(Pt/CNTs) catalysts was studied based on the preparation of CNTs with the single, double and multi walls. The Pt/CNTs catalysts were prepared using liquid phase reduction method. The XRD results demonstrate that the average sizes of the. Pt particles in the Pt/CNTs catalysts with different tube diameters are almost the same (3. 6 nm). However, the electrochemical results indicate that the electrocatalytic activity of the Pt/CNTs catalysts for the methanol oxidation increases with the decrease of the tube diameters of CNTs. The reason can be attributed to that CNTs with the small tube diameter possess large specific surface area and more oxygen-containing groups, which are favorable for the dispersion of the Pt particles in the Pt/CNTs catalysts. In addition, it has been reported in the literature that the resistance of CNTs with the single wall is smaller than that of CNTs with multi walls. Therefore, the above three factors lead to that the electrocatalytic activity of the Pt/CNTs catalysts with the small tube diameter of CNTs for the methanol oxidation is higher than that with the large tube diameter of CNTs.