Synthesis and Photocatalytic Properties of Iron Disilicide/SiC Composite Powder
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Synthesis and Photocatalytic Properties of Iron Disilicide/SiC Composite Powder Kensuke Akiyama1,2, Yuu Motoizumi1, Tetsuya Okuda1, Hiroshi Funakubo2, Hiroshi Irie3 and Yoshihisa Matsumoto1 1 Kanagawa Industrial Technology Center, 705-1 Shimoimaizumi, Ebina, Kanagawa 243-0435, Japan. 2 Tokyo Institute of Technology, Department of Materials Science and Engineering School, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan. 3 University of Yamanashi, Clean Energy Research Center, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan.
ABSTRACT Semiconducting iron disilicide (-FeSi2) island grains of 50-100 nanometers in size were formed on the surface of Au-coated 3C-SiC powder by metal-organic chemical vapor deposition. On the surface of 3C-SiC powder, the Au-Si liquidus phase was obtained via a Au-Si eutectic reaction, which contributed to the formation of the -FeSi2 island grains. This -FeSi2/SiC composite powder could evolve hydrogen (H2) from methyl-alcohol aqueous solution under irradiation of visible light with wavelengths of 420-650 nm.
INTRODUCTION Photocatalytic water splitting is an ideal method for solar energy harvesting. Since Honda and Fujishima reported on the water splitting using TiO2 with Pt photo-electrodes [1], some photocatalysts suitable for water splitting have been discovered. However, the development of visible-light sensitive photocatalysts is indispensable due to the effective utilization of incoming solar energy. On the other hand, semiconducting iron disilicide (-FeSi2) has been attracting a great deal of attention as a photodetector and Si-based light emitter operating at wavelengths suitable for optical fiber communications (1.54 μm) [2,3]. This is because -FeSi2 has a band gap of approximately 0.80 eV and a very large optical absorption coefficient of over 105 cm−1 at 1 eV [4,5]. Moreover, it has recently been reported that this semiconducting material acts as a hydrogen-evolution photocatalyst [6]. As a hydrogen (H2) evolution photocatalyst, -FeSi2 is expected to enable the use of near infrared light longer than 1300nm, which is the longest wavelength of light to be utilized. In the present paper, we report on the fabrication of -FeSi2/SiC composite powder by the metal-organic chemical vapor deposition (MOCVD) which is general preparation method in semiconductor process technology. To prepare the -FeSi2/SiC composite powder, -FeSi2 island grains were formed via a vapor-liquid-solid (VLS) method using the liquidus phase obtained from an Au-Si eutectic reaction during MOCVD growth. The -FeSi2 island grains of 50-100 nanometers in size were formed on the surface of Au-coated 3C-SiC powder. Moreover,
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we report on the hydrogen evolution over this composite powder from methyl-alcohol aqueous solution under irradiation of visible light. EXPERIMENT 3C-SiC powd
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