am al sy sho ture d to e of mmon e inven e impo n, and tic am at a lower reaction temperature and pressure, compared to iron-based cance in this field. the best use of sunlight . As a result of research on energy band a collective oscillation t light, and if the plascture, it is called LSPR ong absorption bands 1,12]. The absorption
Catalysis Communications 59 (2015) 40–44
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Catalysis Com j ourna l homepage: www.e lstemperature (400–600 °C) and high pressure (20–40 MPa) . It consumes a great deal of energy and accounts for around 1–2% of the range is controllable by modifying the size and shape of the particle . The use of LSPR excitation to drive photocatalysis instead ofworldwide energy supply . Any findings that can improve either semiconductors, therefore, is of great significance, opening up newhas no thermodynamic restrictions imposed on conventional catalytic reactors [7,8], and first-principles calculation that is capable of describing the activity of ruthenium catalysts .
Currently, ammonia is manufactured on a large scale by the Haber–
Bosch process, which uses a thermal catalytic reaction, requiring high resonance (LSPR) of metal particles. A plasmon is of the conduction electrons stimulated by inciden mon resonance occurs on a nano-scale fine stru . Gold nanoparticles, for example, exhibit str in the visible light region around 550 nm [1catalysts , Ru/(C12A7:e−) catalysts in which the 12CaO·7Al2O3 support has a high electron-donating ability , metal complexes which induce dinitrogen cleavage and hydrogenation at an ambient temperature and pressure , a proton-conducting cell reactor which modulation, the optical absorption range of photocatalysts has been greatly extended, but the photocatalytic efficiency remains low due to inherent drawbacks .
Recently, great attention has been paid to localized surface plasmon⁎ Corresponding author at: Hazawa-cho 1150, Kan
Kanagawa Prefecture 221-8755, Japan. Tel.: +81 45 374 7
E-mail address: email@example.com (H. Zeng). http://dx.doi.org/10.1016/j.catcom.2014.09.034 1566-7367/© 2014 Elsevier B.V. All rights reserved.[2,3]. The following are alysts which can be used a considerable number of studies have been made to develop photocatalysts with a wide excitation wavelength range that can makebeing conducted as a “never-ending story” some examples of new approaches: Ru/C cat1. Introduction 1.1. Ammonia synthesis
The artificial fixation of nitrogen to a so important to human beings that th process is considered to be much mor than those of the aeroplane, televisio research and development on catalyia (N2+ 3H2→ 2NH3) is tion of the Haber–Bosch rtant in the 20th century computer . Thus, the monia synthesis is still 1.2. Photocatalyst and localized surface plasmon resonance (LSPR)
Titanium oxides, one of the common semiconductor photocatalysts, absorb only ultraviolet light, which accounts formerely 5% of the energy contained in sunlight, and they cannot use visible light that makes up approximately 43% of solar energy . Over the past few decades,the synthesis process or the catalyst performance have a great signifi-Short Communication
A novel catalyst for ammonia synthesis at pressure: Visible light responsive photocat plasmon resonance
Haisheng Zeng ⁎, Shinji Terazono, Toshihiro Tanuma
Asahi Glass Co., Ltd., Research Center, Japan a b s t r a c ta r t i c l e i n f o
Received 11 August 2014
Received in revised form 19 September 2014
Accepted 21 September 2014
Available online 28 September 2014
Localized surface plasmon resonance
A novel catalyst for ammonia
Au composite nanoparticles irradiation at room tempera
Au particles, and contribute rate and the LSPR absorbancagawa Ward, Yokohama City, 591; fax: +81 45 374 8871.bient temperature and yst using localized surface nthesis using localized surface plasmon resonance (LSPR) was investigated. Os– wed a high catalytic activity in ammonia synthesis reaction under visible light and atmospheric pressure. Photo energy was likely to be transferred to Os via the enhancement of the catalytic activity, because the ammonia production
Au particles showed similar dependence on the irradiation wavelength. © 2014 Elsevier B.V. All rights reserved. munications ev ie r .com/ locate /catcompossibilities of making the most of solar energy.
Direct and indirect photocatalyses using LSPR have been studied for a long time, and Kale et al. [13,14] have recently published a review showing that plasmonic nanostructures can be used to drive direct photocatalysis with visible photons, where nanostructures act as both the light absorber and the catalytic active site. Although plasmonic catalysts are reported to be promising, the reaction rates are low and an intense irradiation is indispensable [15,16], indicating that its performance is still far from satisfactory. Regardless of themechanisms for the catalysis relating to LSPR , photo-energy transfer from LSPR particles to catalytic particles appears to be inefficient. 1.3. Ammonia synthesis catalyst using LSPR
Based on the above considerations, we conceived a novel idea of composite nanoparticles for ammonia synthesis of low energyconsuming, by applying catalytically active metal (Os)  directly to
LSPR particles (Au) so that plasmonic energy could be transferred directly and easily to the catalytically active metal particles (Scheme 1).
We propose a hypothesis that excitation of LSPR is used to transfer photon energy to the adjacent catalyst particles, enhancing its catalytic activity. In this study, we prepared Os–Au composite nanoparticles for the ammonia synthesis reaction in order to verify the above hypothesis.
The reaction was carried out under visible-light irradiation at room temperature and ambient pressure. 41H. Zeng et al. / Catalysis Communications 59 (2015) 40–442. Experimental