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| Title: | FABRICATION OF TWO-DIMENSIONAL AND THREE-DIMENSIONAL PLATINUM NANOCLUSTERS TO SERVE AS HIGH TECHNOLOGY CATALYSTS – CATALYTS CAPABLE OF 100% REACTION SELECTIVITY | |
| DOI No: | 10.1142/9789812701879_0013 | |
| Source: | CLUSTERS AND NANO-ASSEMBLIES (pp 97-125) | |
| Author(s): | G. A. SOMORJAI
corresponding author. Department of Chemistry, University of California, Berkeley, CA 94720, USA Lawrence Berkeley, National Laboratory, Materials Science Division, Berkeley, CA 94720, USA R. M. RIOUX Department of Chemistry, University of California, Berkeley, CA 94720, USA Lawrence Berkeley, National Laboratory, Materials Science Division, Berkeley, CA 94720, USA J. GRUNES Department of Chemistry, University of California, Berkeley, CA 94720, USA Lawrence Berkeley, National Laboratory, Materials Science Division, Berkeley, CA 94720, USA |
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| Abstract: | Electron beam lithography and photolithography, followed by size reduction lithography, are carried out to produce two-dimensional nanostructures in the 1–100 nanometer range. The development of size reduction lithography in Berkeley permits parallel formation of 1011 nanowires to provide 1 cm2 surface area nanocluster catalyst that can be used in model studies of catalytic activity and selectivity for comparison with single crystal surfaces. Electron beam lithography, a series preparation technique can only produce 109 nanoparticles or 1 mm2 metal surface area after one day. In most cases, active surface areas of 1 cm2 or more are required for reaction selectivity studies. We shall review the fabrication, cleaning, and characterization of these two-dimensional nanostructure catalysts and their performance in hydrogenation and dehydrogenation reactions, using ethylene and cyclohexene. The metal–oxide interface may be important for several of the catalytic processes that were studied.Three–dimensional nanoclusters with 1015 nanoparticles are prepared by stabilization of the nanoclusters on an inorganic mesoporous support. The large metal content coupled with the high surface-to-volume ratio of nanoclusters leads to 1 m2 of metal surface area. Monodispersed platinum nanoparticles are prepared by alcohol reduction methods and then encapsulated in mesoporous silica, which is prepared by a hydrothermal reaction in the same aqueous solution. The encapsulated particles are reduced to the metallic state, making them active for catalysis. A second synthetic method produces well dispersed nanoclusters on mesoporous silica using a two-step method and low power sonication to facilitate nanocluster diffusion into the silica channels.Two–dimensional and three dimensional nanoclusters which possess controlled spacing and monodispersed metallic nanoclusters, respectively, provide the opportunity to develop green catalysts that demonstrate 100% reaction selectivity. | |
| Full Text: | View full text in PDF format (1260KB) | |
| TOC: | Back to Table of Contents | |
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