Pulsed electrodeposition of Pt particles on indium tin oxide substrates and their electrocatalytic properties for methanol oxidation

The platinum (Pt) particle electrocatalysts supported on the indium tin oxide (ITO) substrate were prepared by the pulsed electrodeposition for the methanol oxidation. The effect of the lower potential pulse duration (tl) of the electrodeposition on the surface morphology and structure of the Pt particles was investigated by the X-ray diffraction and scanning electron microscopy. The amount of the Pt loading was determined by an inductively coupled plasma method, and the electrocatalytic activity of the prepared Pt electrocatalysts on the ITO for the methanol oxidation was characterized by cyclic voltammetry. The results showed that the tl has a significant influence on the surface morphology of the Pt particles on the ITO substrate. As the tl decreases from 1 to 0.01 s, the deposited Pt particles on the ITO exhibit flower-, nanosheet-, prickly and smooth spherical-like morphology in turn. Furthermore, there is a remarkable effect of the surface morphology of the Pt particles on the electrocatalytic activity for the methanol oxidation. Among all these morphologies, the flower- and nanosheet-like Pt particles on the ITO have a much higher mass specific activity (MA) for the methanol oxidation, and the Pt particles with prickly surface followed while the smooth spherical Pt particles have the lowest MA. In particular, the dispersed Pt nanosheets prepared at tl of 0.5 s has the highest MA. The much improved MA of the dispersed Pt nanosheets is attributed not only to the large electrochemically active surface area (ECSA) achieved, but also to the high electrocatalytic activity per unit ECSA related to its special morphology.