Nanosized Metal Catalysts Prepared by an Atomic Layer Deposition Technique

Atomic layer deposition (ALD) is a method for growing single crystals and thin films with the primary advantage that it allows a good conformal coating to obtain nano-particle of metals. This self-controlling feature of ALD allows the growth of uniform compound layers not only on flat substrates but on porous, heterogeneous surfaces. The ALE technique will be applied to produce high dispersion catalysts in this study. In the research reported herein, Cu and Au catalyst with nanoscale particles on oxides supports were prepared using the ALD technique, and apply these catalysts on water-gas shift reaction. In the first year, Cu(thd)2 precursor deposited on SiO2 support will be investigated several issues with respect to the mechanism of deposition process, effect of deposition cycles on Cu particle size and sites on SiO2 interacting with Cu(thd)2 etc. We would like to develop the key technique for preparing the nanosized Cu particles less than 3 nm at high Cu lading. In the second year, the synthesis of Cu particles is expected to further deposited on TiO2, Al2O3, ZnO and CeO2 supports. In the third year, the ALD technique will be developed to prepare various SiO2 supported Au catalysts, using Au(CH3)2(acac) as the precursor. On the other hand, a new technique for bimetallic Cu-Au catalysts prepared is also attempted to synthesize on SiO2 support. The active sites and chemical state of all Cu, Au and Cu-Au catalysts will discussed in relation to the characterization and activity results of the water-gas shift (WGS) reaction. We used CO as a probe molecule to identify the active sites on the ALD catalysts, because it is a good probe molecule for vibrational spectroscopy and can usually provide important information about the surface sites of adsorbed species and the chemical environment of a copper surface. The reaction mechanism of WGS reaction, active sites for H2O adsorbed and H2O dissociation will be investigated by the IR and TPD techniques. We will build up a flow reaction system combining FT-IR, TPD and GC-TCD techniques. On the other hand, FT-IR also will be applied to perform the kinetic parameters for WGS reaction on ALD surface. The fundamental properties of ALD catalysts will be studied in that precursors binding with porous support, decomposition of precursors on support and formation mechanism of metal particle from precursors. We will focus the study on the fundamentally growth of Cu particles on surface. The examination of catalysts, by XAS, EXAFS, DR-UV/VIS, TPR, XRD, AES and ESCA etc., may be associated with experimental results of TPD and IR.

Project ID:PA10101-1797
External Project ID:NSC100-2113-M182-001-MY3