Abstract: Nano-flocculent-Co₃O₄ modified multi-walled carbon nanotubes supported Pd nanoparticles (Pd-Co₃O₄/MWCNTs) with uniform dimensions were prepared by a facile hydrothermal method using Co(NO₃)₃·6H₂O as the cobalt source, polyethylene glycol (PEG) 20000 as a surface active agent, and H₂PdCl₄ as the Pd precursor. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray powder diffraction. The Pd nanoparticles had a face-centered cubic crystal structure and were well dispersed on the external walls of the Co₃O₄/MWCNTs. The catalytic activity was studied by cyclic voltammetry and chronoamperometry toward methanol oxidation. The Pd-Co₃O₄/MWCNT catalysts had a large electrochemically active area, good electrocatalytic performance, and stability toward methanol oxidation in alkaline media. All the results suggest that Co₃O₄ will improve the electrocatalytic activity in direct methanol fuel cells.

Key words: Direct methanol fuel cell, Co₃O₄, Hydrothermal method, Pd, Multi-walled carbon nanotubes, Electrocatalytic oxidation