title: Photoelectrochemical water splitting enhanced by self-assembled metal nanopillars embedded in an oxide semiconductor photoelectrode.
abstract: Production of chemical fuels by direct solar energy conversion in a photoelectrochemical cell is of great practical interest for developing a sustainable energy system. Various nanoscale designs such as nanowires, nanotubes, heterostructures and nanocomposites have been explored to increase the energy conversion efficiency of photoelectrochemical water splitting. Here we demonstrate a self-organized nanocomposite material concept for enhancing the efficiency of photocarrier separation and electrochemical energy conversion. Mechanically robust photoelectrodes are formed by embedding self-assembled metal nanopillars in a semiconductor thin film, forming tubular Schottky junctions around each pillar. The photocarrier transport efficiency is strongly enhanced in the Schottky space charge regions while the pillars provide an efficient charge extraction path. Ir-doped SrTiO3 with embedded iridium metal nanopillars shows good operational stability in a water oxidation reaction and achieves over 80% utilization of photogenerated carriers under visible light in the 400- to 600-nm wavelength range.
authors.affiliation: Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kawasaki
authors.affiliation: Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Takahashi
authors.affiliation: Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kumigashira
authors.affiliation: Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshinobu
authors.affiliation: Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Komori
authors.affiliation: Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Tokyo 162-8601, Japan.|Photocatalysis International Research Center, Research Institute for Science and Technology, Tokyo University of Science, 2641 Noda, Yamazaki 278-8510, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kudo
authors.affiliation: Institute for Solid State Physics (ISSP), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8581, Japan.
authors.forename: Mikk
authors.initials: M
authors.lastname: Lippmaa