title: Thermo-stable carbon nanotube-TiO₂ nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process.
abstract: We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.
authors.affiliation: Frontier Research Labs, Institute for Innovation, Ajinomoto Co., Inc., 1-1, Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan.
authors.forename: Ippei
authors.initials: I
authors.lastname: Inoue
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yamauchi
authors.forename: Naofumi
authors.initials: N
authors.lastname: Okamoto
authors.forename: Kenichi
authors.initials: K
authors.lastname: Toyoda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Horita
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Hisashi
authors.initials: H
authors.lastname: Yasueda
authors.forename: Yukiharu
authors.initials: Y
authors.lastname: Uraoka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yamashita
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D055664:Electrochemical Techniques; D004583:Electrons; D005293:Ferritins / Q000737:chemistry / Q000235:genetics; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010777:Photochemistry / Q000379:methods*; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D037742:Nanotubes, Carbon; C009495:titanium dioxide; D005293:Ferritins; D014025:Titanium