Layer-by-Layer Pt Growth on Polycrystalline Au: Surface-Limited Redox Replacement of Overpotentially Deposited Ni Monolayers

The catalyst system Pt/Au has been the subject of many studies recently, ranging from formic acid oxidation to oxidative studies for direct alcohol fuel cells. This paper outlines the use of overpotential Ni deposition as an intermediary for the creation of model overlayer/substrate Pt/Au catalysts with atomic monolayer (ML)-level thickness control. Deposition of Pt on polycrystalline Au was conducted via Ni surface-limited redox replacement. By electrodepositing a controlled layer of Ni on Au and exposing the resultant surface to Pt in solution, then repeating this technique for multiple iterations, Pt atomic MLs were electrolessly deposited on top of one another. The growth of Pt overlayers was demonstrated by X-ray photoelectron spectroscopy. The use of Ni as the replacement layer, as opposed to the commonly used Cu, opens up a range of metals for layer-by-layer deposition. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3224113] All rights reserved.