Disperse Barium Oxide Nanoislands Synthesized on Aluminum Oxide by Successive Ionic Layer Deposition

Thomas I. Gilbert and Johannes W. Schwank. Chemical Engineering, University of Michigan, 2300 Hayward St, 3074 H.H. Dow Building, Ann Arbor, MI 48109-2136

Successive Ionic Layer Deposition (SILD) is an aqueous technique to deposit nanolayers of oxide materials on a substrate in an organized manner. With each SILD cycle submonolayers of metal hydroxides are strongly adsorbed on the substrate using precursor solutions of dilute aqueous metal salts. Varying the SILD synthesis conditions changes the chemistry and morphology at the nanometer scale.

Catalysis has always been a nanoscale science. The interface between the active metal catalyst and the support is believed to be a particularly active site in some catalytic systems. Increasing the dispersion of a catalyst on a support not only increases the overall catalyst surface area but also leads to a higher concentration of metal-support interactions. It has been reported that a dispersed phase of BaO on Al2O3 plays a major role in NOx emission control catalysis for lean burn engines. [1] However, conventional catalyst synthesis techniques tend to produce primarily a bulk-like phase of barium oxide as more catalyst is loaded onto the aluminum oxide support. SILD offers the opportunity to exclusively synthesize the dispersed phase of BaO on Al2O3 and study its properties.

In this poster, we describe how SILD was used to deposit disperse nanoislands of BaO on islands of Al2O3 supported on silicon wafer substrates. These nanomaterials were studied as model catalytic surfaces and characterized by techniques such as Atomic Force Microscopy, Scanning Electron Microscopy, and X-ray Photoelectron Spectroscopy.


1. X. Chen, J. Schwank, J. Li, W.F. Schneider, C.T. Goralski, P.J. Schmitz, Appl. Catal. B Environ. 61 (2005).