Nanospace-controlled gold material created using molecular technology

June 8, 2015, National Institute for Materials Science
Nanospace-controlled gold material created using molecular technology
Electron micrographs of nanoporous gold materials that were fabricated using different sizes of micelles. Pore size increases from left to right.

A research group led by Yusuke Yamauchi, an Independent Scientist at the International Center for Materials Nanoarchitectonics (MANA), NIMS, in cooperation with other research organizations in Japan and overseas, successfully developed a nanoporous gold material with a regular, uniform pore arrangement using polymers as a template.

Nanoporous materials, having internal pores of several-nanometers in diameter and a large surface-to-volume ratio, have the potential of producing novel chemical reactions, and thus have been vigorously studied in the pursuit of developing new catalyst and absorbent materials. In particular, it has been proposed to apply nanoporous gold materials to various fields such as electronics, catalysts and medicine, and it has been reported that they were processed into various forms such as , gold nanorods and gold nanowires. However, these conventional nanoporous gold materials have rather irregular pore arrangements, and it had been hoped to fabricate nanoporous gold materials whose can be freely manipulated.

In recent years, it has become feasible to synthesize mesoporous metals with a metal framework by using amphipathic molecules (e.g., surfactants) as a template. In this study, we created uniformly sized spherical micelles (molecular assembly) by adjusting the concentration of polymers that possess both hydrophobic and hydrophilic properties (amphipathic ) in a dilute solution. Using these polymers as a template, we reduced while precisely controlling electrolytic deposition, resulting in the successful formation of nanopores, whose sizes corresponded to the sizes of the micelles used, over the surfaces of the gold films.

In the pores of the nanoporous gold materials, we observed a strong electric field and surface enhanced Raman scattering (SERS). It is expected that these distinctive properties will have various applications such as a SERS-activate substrate for molecular sensing and electrode catalyst. Also, this technology is applicable to various metals and alloys in addition to gold. Furthermore, since pore size can be adjusted to various diameters by changing the molecular size of the block copolymers, it is feasible to design metal nanospace materials that meet specific needs of users in terms of composition and structure.

This research was conducted as a part of the bioelectronics and biophotonics project sponsored by the JST's program "Infrastructure Development for Promoting International Science and Technology Cooperation."

Explore further: Holes in gold enhance molecular sensing

More information: "Electrochemical synthesis of mesoporous Au films toward mesospace-stimulated optical properties", DOI: 10.1038/ncomms7608

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NIPSZX
not rated yet Jun 08, 2015
I have heard many stories of gold being created synthetically, even dating back ten years. The price of gold still is higher today, compared to ten years ago. I guess it might cost more to create gold synthetically than it costs to mine. At least for now.

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