Abstract: The electrochemical preparation of shape-controlled palladium nanoparticles(PdNPs) and their catalytic activity toward methanol electrooxidation were reported. PdNPs were prepared on indium tin oxides(ITO) conductive substrates by a two-step constant potential deposition method, in which Na2PdCl4 and citrate were used as precursor and capping agent. The morphology, size, and growing density of PdNPs can be controlled by varying the electrodeposition parameters, such as nanoseeds generation potential, particle growth potential, the concentration of citrate and bromide, and the deposition temperature. The Pd nanohorn arrays, spherical, flower-like and polyhedronal PdNPs were  prepared on ITO substrates. The electrocatalytic properties for methanol oxidation on PdNPs with different morphologies were investigated in alkaline solution. Compared with other PdNPs, the Pd nanohorns demonstrated a much larger surface area on an ITO substrate with a fixed area due to their larger height. As a result, the Pd nanohorn arrays exhibite a higher catalytic activity toward methanol electrooxidation, making them a potential candidate for alkaline direct fuel cell anode materials.

Key words: Palladium nanoparticle, Electrodeposition, Indium tin oxides(ITO) conductive glass, Methanol, Electrocatalysis