(Invited) Fabrication of Micro- and Nanostructures for High Efficiency Energy Conversion By Using Anodic Porous Alumina

The fabrication of micro - and nanostructured materials with controlled geometrical structures has attracted increasing interest for the preparation of various types of energy conversion devices with high efficiencies.  The use of the material, which has naturally occurring ordered structures, is effective for the fabrication of the micro- and nanostructures of various kinds of materials.  Anodic porous alumina, which is formed by anodization of Al in acidic solution, is a promising candidate for the fabrication of micro- and nanostructured materials with controlled geometrical structures^1,2.  One of commonly used process for the fabrication of micro- and nanostructures using anodic porous alumina is a template synthesis^3,4.  This process can generate the micro- and nanostructures with controlled geometrical structures, which are useful for the fabrication of high efficient energy conversion devices.  However, the problem of the usual template synthesis is the low throughput due to the difficulty of the repeated use of the template.  To solve this problem, we have been studying the new types of processes, which allow the high throughput formation of micro- and nanostructures.  In the present report, recent results concerning the high throughput fabrication process for the micro- and nanostructures of metals and metal oxides, which can be applied to the energy conversion devices.  The processes include the molding fabrication process for metal nanowires, and the membrane emulsification for uniform sized nanoparticles of metal oxides^5,6 by using anodic porous alumina.  These processes allow the high throughput fabrication of micro- and nanostructures because the starting structures of anodic porous alumina can be used many times.  The obtained micro- and nanostructures will be useful for the fabrication of energy conversion devices with high efficiency due to their precisely controlled geometrical fine structures. 

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2. H. Masuda and K. Fukuda, Science, 268, 1466 (1995).

3. K. Yasui, T. Morikawa, K. Nishio, and H. Masuda, Jpn. J. Appl. Phys., 15, L469 (2005).

4. T. Kondo, T. Fukushima, K. Nishio, and H. Masuda, Appl. Phys. Express, 2, 125001 (2009).

5. T. Yanagishita, R. Fujimura, K. Nishio, and H. Masuda, Langmuir, 26, 1516 (2009).

6. T. Yanagishita, Y. Maejima, K. Nishio, and H. Masuda, RSC Adv., 4, 1538 (2014).