Fabrication of Dense Arrays of Platinum Nanowires on Silica, Alumina, Zirconia and Ceria Surfaces as 2-D Model Catalysts
- PDF / 507,343 Bytes
- 6 Pages / 595.276 x 793.701 pts Page_size
- 66 Downloads / 181 Views
Catalysis Letters Vol. 105, Nos. 3–4, December 2005 ( 2005) DOI: 10.1007/s10562-005-8681-x
Fabrication of dense arrays of platinum nanowires on silica, alumina, zirconia and ceria surfaces as 2-D model catalysts X.-M. Yana,*, S. Kwonb, A.M. Contrerasa,c, M.M. Koebelc, J. Bokorb,e and G.A. Somorjaia,c,d a Department of Chemistry, University of California, Berkeley, 94720 CA The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA c Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA d Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, 94720 CA e Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA 94720 b
Received 1 July 2005; accepted 24 August 2005
High-density arrays of platinum nanowires with dimensions 20 nm 5 nm 12 lm (width height length) have been produced on planar oxide thin films of silica, alumina, zirconia, and ceria. In this multi-step fabrication process, sub-20 nm single crystalline silicon nanowires were fabricated by size reduction lithography. The Si nanowire patterns were then replicated to produce a high density of Pt nanowires by nanoimprint lithography. The width and height of the Pt nanowires are uniform and are controlled with nanometer precision. The Pt surface area is larger than 2 cm2 on a 5 5 cm2 oxide substrate. The catalytic oxidation of CO was carried out on zirconia-supported Pt nanowires. The reaction conditions (100 Torr O2, 40 Torr CO, 513–593 K) and vacuum annealing (1023 K) did not change the nanowire structures. KEY WORDS: platinum nanowires; two-dimensional model catalysts; oxide-supported platinum nanowires.
1. Introduction Transition metal catalysts usually consist of nanoparticles in the 1–100 nm size-range deposited on high surface-area supports. The particle size, surface structure and the oxide–metal interface all influence catalytic activity, selectivity, and resistance to deactivation. Model metal catalysts, usually in the form of single crystals, have been used with success to elucidate many of the atomic scale ingredients that influence, catalytic performance. Single crystals, however, lack the oxide– metal interface and small particle sizes of an industrial catalyst. So, there has been much effort to develop a model system that offers a choice of oxide–metal interface as well as control over metal structures on a nanometer scale. Several methods have been reported to prepare 2-D model nanoparticle catalysts, including laser ablation [1], spin coating of metal salt solutions on oxide supports followed by calcinations [2], evaporation of metal onto an oxide support [3–5], soft landing of size-selected clusters onto a planar support [6,7], decomposition of transition metal carbonyls [8], laser interference nanolithography [9], photolithography [10], colloidal lithography [11], and electron-beam lithography [12] (EBL). However, all of the above listed methods have deficiencies: (1) Non-lithography methods were able to access the cataly
Data Loading...
