Success in Fabrication of Mesoporous Metal with Giant Mesocage Structure

A New Development in Mesoporous Metals, A New Proposal for Metallic Nanostructures

2008.06.09

National Institute for Materials Science

Dr. Yusuke Yamauchi, a MANA Young Scientist at the International Center for Materials Nanoarchitechtonics, National Institute for Materials Science, succeeded in fabricating mesoporous metal with a giant mesocage structure using an electrochemical technique. In this work, a molecular assembly formed by self-assembly of a block copolymer which is an amphipathic molecule at large sizes was used as a template.

Abstract

  1. Dr. Yusuke Yamauchi, a MANA Young Scientist at the International Center for Materials Nanoarchitechtonics (MANA; Director-General: Masakazu Aono), National Institute for Materials Science (President: Teruo Kishi), succeeded in fabricating mesoporous metal with a giant mesocage structure using an electrochemical technique. In this work, a molecular assembly formed by self-assembly of a block copolymer which is an amphipathic molecule at large sizes was used as a template.
  2. Mesoporous metals, which have a regular pore arrangement and large surface area, provide a frame that consists solely of metal, and thus are promising candidates for an electrochemically wide range of applications which are not possible with conventional silica-based mesoporous substances. In synthesis of conventional mesoporous substances, it is possible to control the pore diameter over a wide range, from several nm to several 10nm. At present, however, the pore diameter of mesoporous metals is limited to 3-4nm. Therefore, mesoporous metals with a large pore structure had been demanded in order to realize access by large molecules and improved diffusion of substances.
  3. To overcome this problem, Dr. Yamauchi formed a large-sized molecular assembly by self-assembly of a molecularly-designed block polymer, and using this as a direct template, reduced platinum ions while precisely controlling the electrodeposition process. This resulted in successful synthesis of mesoporous platinum with a large pore diameter exceeding 10nm, i.e., giant mesocages, which had not been achieved until now.
  4. Giant mesocages make it possible to introduce large molecules into the matrix structure, which was not possible with the conventional small diameter pore structure, and thus enable efficient electrochemical reaction of various species of large guest molecules with the metallic surface of the pores. This technology is not limited to platinum, but can also be applied to various other metals and alloys. Furthermore, the pore size can be controlled over a wide range by varying the size of the block copolymer molecules, enabling “tailor-made” design of electrode materials with applications taking advantage of both compositional and structural features.
  5. This research achievement received the Excellence Award for Scientific Photography at the Annual Meeting of the Ceramic Society of Japan in this spring, and is scheduled for publication in the near future in the spot news section "Communication" of "Angewandte Chemie-International Edition," which is published by the German Chemical Society.
[Published Paper]
Yusuke Yamauchi, Atsushi Sugiyama, Ryoichi Morimoto, Azusa Takai, and Kazuyuki Kuroda: "Mesoporous Pt with Giant Mesocages Templated from Lyotropic Liquid Crystals Consisting of Diblock Copolymers by Electrochemical Deposition," Angewandte Chemie-International Edition, in press (2008).
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