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Chem. Mater. 2000, 12, 3530-3532
Synthesis of Porous Palladium Superlattice Nanoballs and Nanowires Hongkyu Kang, Young-wook Jun, Jong-Il Park, Kyung-Bok Lee, and Jinwoo Cheon* Department of Chemistry and School of Molecular Science-BK21, Korea Advanced Institute of Science and Technology (KAIST), Taejon 305-701, Korea Received July 26, 2000 Revised Manuscript Received September 29, 2000 Over the past decade, interest has grown in the synthesis of nanosized materials because of their novel electronic, optical, and catalytic properties.1 Of the various methods available to prepare these materials, one of the most interesting is templated synthesis where the desired nanomaterial is encapsulated into the channels and pores of a host.2 In particular, mesoporous solids with pore size tunability ranging from ≈2 to ≈30 nm have been the focus of special attention as hosts for quantum dots and wires.3 For example, the pores of various mesoporous materials have been filled with polymers, semiconductors (CdS, GaAs, InP, GaN), metal oxides (Fe2O3), and metals (Ag, Pd, Pt) by either simple solution or vapor infiltration processes.4 These processes, however, are often unable to fill the pores completely and sometimes generate undesired materials outside the host pores. In addition, the intimate contact between the host and guest can adversely affect the properties of the guest as has been observed for InP nanoparticles inside a zeolite.5 There are two important objectives in nanomaterials synthesis. First, it is advantageous to develop methods to synthesize nanoparticles free of the template hosts. Second, because the catalytic and physical properties of a nanoparticle strongly depend on its size and shape, (1) See the reviews by (a) Schmid, G. Chem. Rev. 1992, 92, 1709. (b) Alivisatos, A. P. J. Phys. Chem. 1996, 100, 13226. (c) Alivisatos, A. P. Science 1996, 271, 933. (d) Steigerwald, M. L.; Brus, L. E. Acc. Chem. Res. 1990, 23, 183. (2) (a) Martin, C. R. Science 1994, 266, 1961. (b) Martin. C. R. Chem. Mater. 1996, 8, 1739. (c) Kyotani, T.; Tsai, L.-F.; Tomita, A. J. Chem. Soc., Chem. Commun. 1997, 701. (d) Routkevitch, D.; Bigion, T.; Moskovits, M.; Xu, J. M. J. Phys. Chem. 1996, 100, 14037. (e) Ozin, G. A.; Kuperman, A.; Stein, A. Angew. Chem., Int. Ed. Engl. 1989, 28, 359. (3) (a) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S. Nature 1992, 359, 710. See some reviews: (b) Zhao, D. Y.; Yang, P. D.; Huo, Q. S.; Chmelka, B. F.; Stucky, G. D. Curr. Opin. Solid State Mater. Sci. 1998, 3, 111. (c) Raman, N. K.; Anderson, M. T.; Brinker, C. J. Chem. Mater. 1996, 8, 1682. (d) Sayari, A. Chem. Mater. 1996, 8, 1840. (e) Ying, J. Y.; Mehnert, C. D.; Wong, M. S. Angew. Chem., Int. Ed. Engl. 1999, 38, 56. (f) Brinker, C. J. Curr. Opin. Solid State Mater. Sci. 1996, 1, 798. (g) Corma, A. Chem. Rev. 1997, 97, 2373. (4) (a) Moller, K.; Bein, T. Chem. Mater. 1998, 10, 2950 and references therein. Some recent studies: (b) Srdanov, V. I.; Alxneit, I.; Stucky, G. D.; Reaves, C. M.; DenBaars, S. P. J. Phys. Chem. B 1998, 102, 3341. (c) Agger, J. R.; Anderson, M. W.; Pemble, M. E.; Terasaki, O.; Nozue, Y. J. Phys. Chem. B 1998, 102, 3345. (d) Winkler, H.; Birkner, A.; Hagen, V.; Wolf, I.; Fischer, R. A.; Schmechel, R.; Seggern, H. V. Adv. Mater. 1999, 11, 1444. (e) Wang, L.-Z.; Shi, J.-L.; Zhang, W.-H.; Ruan, M.-L.; Yu, J.; Yan, D. S. Chem. Mater. 1999, 11, 3015. (f) Mehnert, C. P.; Weaver, D. W.; Ying, J. Y. J. Am. Chem. Soc. 1998, 120, 12289. (g) Yamamoto, T.; Shido, T.; Inagaki, S.; Fukushima, Y.; Ichikawa, M. J. Phys. Chem. B 1998, 102, 3886. (5) Trave, A.; Buda, F.; Fasolino, A. Phys. Rev. Lett. 1996, 77, 5405.
it is important to devise methods that allow significant control over these morphological attributes. To date, only a few studies have achieved both of these goals in mesoporous template approaches: One of the studies used the two-step nanocasting process where mesoporous organic networks were grown by polymerization of monomers and subsequent removal of a silicate matrix.6a,b Excellent carbon-based mesoporous materials were also obtained from a MCM-48 template.6c,d As opposed to well-known inorganic oxides or ceramics, the fabrication of stable metallic structures with ordered nanopores of
