Pulsed Galvanostatic Deposition of Pt Particles on Microcrystalline and Nanocrystalline Diamond Thin-Film Electrodes

Abstract

The pulsed galvanostatic deposition of nanometer-sized Pt particles on electrically conducting microcrystalline and nanocrystalline diamond thin-film electrodes is reported. The deposition was studied as a function of pulse number (10-50) and current density at the two morphologically different forms of diamond. The deposition of catalyst particles using ten pulses (duty cycle 50%) at a current density of (geometric area) produced the smallest nominal particle size and the highest particle coverage on both diamond surfaces. Secondary electron micrographs revealed metal particle deposition over much of the diamond surface, a nominal particle size of [relative standard deviation ] for microcrystalline and for nanocrystalline diamond, and a nominal particle coverage of for microcrystalline and for nanocrystalline diamond. Deposition under these conditions resulted in the most efficient utilization of the metal catalyst for adsorption, based on the electrochemically active Pt area normalized to the estimated metal loading. Typical specific surface areas of Pt were calculated, which compare favorably to values obtained at electrodes, like carbon and graphite. The influence of the diamond electrode microstructural and electronic properties on the formation of dimensionally uniform metal adlayers is discussed.