Deposition and electrocatalytic properties of platinum nanoparticals on carbon nanotubes for methanol electrooxidation

The electrochemical deposition and the electrocatalytic properties of platinum (Pt) nanoparticles on carbon nanotube electrode have been investigated in this paper. Carbon nanotubes (CNTs) used in this paper are grown directly on graphite disk by chemical vapor deposition (CVD). The Pt nanoparticles are synthesized by potentiostatic method from 1.3 mM chloroplatinic acid + 0.5 M sulfuric acid aqueous solution at −0.25 V. The micrographs of Pt/CNTs/graphite electrode are characterized by scanning electron microscopy (SEM). The electrocatalytic properties of Pt/CNTs/graphite electrodes for methanol oxidation have been investigated by cyclic voltammetry (CV) in 1.0 M CH3OH+0.5 M H2SO4 aqueous solutions and the excellent electrocatalytic activity (AQ, defined by peak current density per unit of Pt deposition charge) can be observed even at low platinum deposition charge (Q=1.24×10−4 C cm−2). At Q=3.72×10−3 C cm−2, the highest electrocatalytical activity of Pt/CNTs/graphite electrode reaches 4.62 A C−1 and is about 2.3 times as high as that of Pt/graphite electrode. This may be attributed to the unique structure and high surface area of carbon nanotubes and also suggests that CNTs have good potential applications as catalyst supports in direct methanol fuel cell (DMFC). On the other hand, the long-term stability of Pt/CNTs/graphite electrode has also been investigated.