Electrochemical Deposition of Platinum Hydrosol on Graphite Observed by Scanning Tunneling Microscopy

Abstract

Ligand stabilized metal colloids are discussed as promising candidates for metal catalyst precursors or even supported catalysts. The protective shell around the metal particles prevents their agglomeration and leads to a highly dispersed metal phase. A narrow metal particle size distribution, as revealed by transmission electron microscopy, is achieved by specific reduction techniques. These catalysts are generally prepared by adsorption, i.e., by adding the support material to the colloidal solution, followed by a drying step. Another way to prepared supported catalysts is electrophoretic deposition, which was recently demonstrated for a gold colloid. For conductive supports, such as carbon, an electrochemical deposition of colloids can be envisioned also. To our knowledge this has not been investigated yet. In this note the authors present, first, the results of a combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) study on the electrochemical deposition of platinum nanocolloids with an organic shell (hydrosol) onto highly oriented pyrolytic graphite (HOPG). 7 refs., 3 figs.