Paper SE-ThP11
Highly Conformal and Size-Controlled Nanofabrication of Macro-scale Three-Dimensional Biotemplated Inorganic Nanonetworks

Thursday, October 31, 2013, 6:00 pm, Room Hall B

By combining organic and inorganic nanomaterials using two different material growth techniques (self assembly and atomic layer deposition), we demonstrate a facile and reliable fabrication method for TiO₂ and ZnO semiconductor nanonetworks. Self-assembled peptide-amphiphile nanofibers are used as three-dimensional organic nano-templates, whereas subsequently atomic layer deposited metal-oxide films formed the conformal inorganic functional nano-coatings. Apart from the traditional organic templates, we used a fully dried, three-dimensional (cm-scale), highly interconnected peptide nanofibrous network template, which enabled atomic layer deposition (ALD) precursors to be homogenously deposited with exceptional conformity. The wall thickness of the inorganic nanotubes can be precisely controlled by simply altering the number of ALD cycles. TiO₂ and ZnO nanonetworks demonstrated superior performance compared to the unstructured TiO₂ and ZnO substrates in photocatalytic activity because of the enhanced specific surface area of the photocatalysts with nanostructured morphology. Importantly, immobilization of the photocatalysts on a solid support enabled recycling of the material, which can dramatically reduce the treatment cost and prevent secondary contamination of the water sources with inorganic materials. Furthermore, we discovered that there is an optimal wall thickness for gaining photocatalytic advantage through nanostructuring for both TiO₂ and ZnO. This optimum nanotube wall thickness was found to be around ~8 nm for both TiO₂ and ZnO. These results demonstrate significant potential of using peptide-based organic templates to fabricate high-quality TiO₂ and ZnO nanostructures not only for photocatalysis, but for several applications where increased surface area plays a crucial role: chemical/gas sensing, dye synthesized solar-cells , etc. Further studies can be extended to other transition-metals and their compounds, such as oxides, nitrides, and sulfides. As a result of the rapid and convenient scaling of the peptide nanofibers into macro-size networks, new opportunities could be available for fabrication of a wider range of inorganic materials.