Ryuhei Nakamura

Nitrogen doping of anatase TiO2 powder extended the photocurrent action spectrum for water oxidation from the UV-light region (≤400 nm) to the visible-light region (≤ ∼550 nm), as reported. Investigations of the effect of the addition of reductants such as methanol, SCN-, Br-, I-, and hydroquinone to the electrolyte have for the first time given clear experimental evidence to the mechanism that visible-light responses for N-doped TiO2 arise from an N-induced midgap level, formed slightly above t

Primary intermediates of oxygen photoevolution (water photooxidation) reaction at the TiO2 (rutile)/aqueous solution interface were investigated by in situ multiple internal reflection infrared (MIRIR) absorption and photoluminescence (PL) measurements. UV irradiation of TiO2 in the presence of 10 mM Fe3+ in the solution caused the appearance of a new peak at 838 cm(-1) and a shoulder at 812 cm(-1). Detailed investigations of the effects of solution pH, the presence of methanol as a hole scaveng

Hexavalent iridium (Ir^VI) oxide is predicted to be more active and stable than any other iridium oxide for the oxygen evolution reaction in acid; however, its experimental realization remains challenging. In this work, we report the synthesis, characterization, and application of atomically dispersed Ir^VI oxide (Ir^VI-<i>ado</i>) for proton exchange membrane (PEM) water electrolysis. The Ir^VI-<i>ado</i> was synthesized by oxidatively substituting the li

Multiple internal reflection infrared spectroscopy was applied to in situ investigations of surface intermediates of photocatalytic reactions on nanocrystalline TiO(2) films in contact with aqueous solutions. UV irradiation in the presence of dissolved O(2) caused the appearance of new bands peaked at 943, 838, and 1250-1120 cm(-)(1) together with intensity changes in other bands. Investigations of influences of the solution pH, the presence or absence of hole and electron scavengers, and isotop

Efficient, earth-abundant, and acid-stable catalysts for the oxygen evolution reaction (OER) are missing pieces for the production of hydrogen via water electrolysis. Here, we report how the limitations on the stability of 3d-metal materials can be overcome by the spectroscopic identification of stable potential windows in which the OER can be catalyzed efficiently while simultaneously suppressing deactivation pathways. We demonstrate the benefits of this approach using gamma manganese oxide (γ-

Protein power grids: A metal-reducing bacterium, Shewanella loihica PV-4, has the ability to self-organize an electrically conductive network using outer-membrane proteins and semiconductive minerals as a long-distance electron transfer conduit. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not respons

The success in preparing atomically smooth and stable (110) and (100) TiO2 (rutile) surfaces, combined with in situ photoluminescence (PL) and photocurrent measurements as well as atomic force microscopic (AFM) inspection, has enabled us to make systematic studies on molecular mechanisms of oxygen photoevolution and related processes on TiO2 (rutile), which are important for solar water splitting and photocatalytic environmental cleaning. The studies have revealed that various surface processes

The first photocatalysis operated by the visible-light induced metal-to-metal charge transfer (MMCT) has been demonstrated for the Ti(IV)/Ce(III) bimetallic assemblies synthesized on the pore of mesoporous silica. The Ce LIII-edge XANES measurements combined with 18O-isotopic labeling as well as photoelectrochemical experiments proved the ability of Ti(IV)/Ce(III) assemblies to drive the site-specific photocatalytic reaction under visible-light irradiation. Photocatalytic experiments using the o

Abstract Current high‐performance thermoelectric materials require elaborate doping and synthesis procedures, particularly in regard to the artificial structure, and the underlying thermoelectric mechanisms are still poorly understood. Here, we report that a natural chalcopyrite mineral, Cu 1+x Fe 1−x S 2 , obtained from a deep‐sea hydrothermal vent can directly generate thermoelectricity. The resistivity displayed an excellent semiconducting character, and a large thermoelectric power and high

Nitrate is a pervasive aquatic contaminant of global environmental concern. In nature, the most effective nitrate reduction reaction (NRR) is catalyzed by nitrate reductase enzymes at neutral pH, using a highly-conserved Mo center ligated mainly by oxo and thiolate groups. Mo-based NRR catalysts mostly function in organic solvents with a low water stability. Recently, an oxo-containing molybdenum sulfide nanoparticle that serves as an NRR catalyst at neutral pH was first reported. Herein, in a n

Shewanella is an electrogenic microbe that has significant content of c type cytochromes (ca. 0.5 mM). This feature allows the optical absorption spectra of the cell-membrane-associated proteins to be monitored in vivo in the course of extracellular respiratory electron-transfer reactions. The results show significant differences to those obtained in vitro with purified proteins.

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct upt

Essentially atomically smooth (100) and (110) n-TiO(2) (rutile) surfaces were prepared by immersion of commercially available single-crystal wafers in 20% HF, followed by annealing at 600 degrees C in air. The obtained surfaces were stable in aqueous solutions of pH 1-13, showing no change in the surface morphology on an atomic level, contrary to atomically flat surfaces prepared by ion sputtering and annealing under UHV. The success in preparation of the atomically smooth and stable n-TiO(2) su