Fabrication and characterization of the Ag-based high technologymodel nanocluster catalyst for ethylene epoxidation manufactured byelectron beam lithography

Nanocluster catalysis is an area where greater fundamental knowledge is needed to understand the behavior of aggregates of metal atoms in determining product selectivity of chemical reactions. While catalysis is practiced industrially with economic success there is still a great need to eliminate wasteful side-reactions which hurt overall yields. Here we report on fabrication of a Ag-based high-technology model nanocluster catalyst by using electron beam lithography (EBL) designed for systematic studies of the ethylene epoxidation reaction. The catalyst is made of a square array of cylinder-shaped Ag nanoclusters that are 200 Angstrom in diameter, deposited on a four inch silicon wafer, precovered with a 100 Angstrom thick film of alpha-alumina. The height of the particles and interparticle distance can vary, and were chosen to be 150-300 and 1000 Angstrom, respectively. The high technology catalyst was characterized by X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The thermal stability of Ag nanoclusters in vacuo was investigated.