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Innovative method for confining metallic nanoparticles in clay nanotubes for catalytic applications


Co-author Katsuhiko Ariga of WPI-MANA, National Institute for Materials Science, Tsukuba shares his insights into the composite 'green' nanomaterials published in Science and Technology of Advanced Materials, that have wide ranging industrial applications including catalysts for decomposing harmful exhaust gases from automobiles.

Iron, platinum and other such metals play an important role in promoting chemical reaction during the production of chemicals such as ammonia that is essential for the manufacture of fertilizers for agriculture.

The performance of catalysts, for example the efficiency of decomposing harmful exhaust gases from automobiles gases, depends on the size and composition of materials, with nanometers metallic compounds offering large relative surface areas and hence the possible to high efficiencies. Here, the researchers used halloysite clay nanotube templates (aluminosilicate clay minerals) to load with 9 wt% of Ru and Ag by Shiff base binding, where "elongated heavy metal particles of 3-4 nm diameter were formed both on the inner lumen surface and in the interlayer slit-like pockets of the halloysite walls".

Analysis showed that metal nanoparticles (Ru, Ag, Rh, Pt, and Co) with diameters ranging from 2 to 5 nm were formed both in the central lumen (the inside space of the tubes) as well as the spaces between the tube walls. The researchers state that, "Halloysite, our nanotemplate of choice, is inexpensive and available in large quantities (thousands of tons) in the form of clay."

Katsuhiko Ariga was honored to receive the award, adding, "The research described in this paper is the result of an international collaboration with colleagues at the Gubkin russian State University of Oil and Gas, Moscow, WPi-MANA, and the Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA. We would like to thank the STAM editorial board for selecting our work for this prestigious award. We hope that the report will encourage other researchers to build on our findings, especially for industrial applications of halloysite nanotemplates based nanocomposite catalysts."

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Source: National Institute for Materials Science, Japan