Gold Nanoparticles Supported on SrTiO 3 by Solution Plasma Sputter Deposition for Enhancing UV- and Visible-light Photoc
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Gold Nanoparticles Supported on SrTiO3 by Solution Plasma Sputter Deposition for Enhancing UV- and Visible-light Photocatalytic Efficiency Gasidit Panomsuwan 1, Nobuyuki Zettsu 1,3, and Nagahiro Saito 1−3 1 Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan 2 EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan 3 Green Mobility Collaborative Research Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan ABSTRACT Gold (Au) nanoparticles were synthesized and deposited on the perovskite SrTiO3 (STO) via a one-step solution plasma sputter deposition (SPSD) without any reducing reagents at ambient condition. Good dispersion of the Au nanoparticles deposited on the STO surface was clearly observed. The synthesized Au nanoparticles were well-crystallized with a spherical shape and preferably exhibited multiply twinned structure. An average diameter of Au nanoparicles was estimated to be 6.1 ± 1.4 nm by transmission electron microscopy. Enhanced photocatalytic activity was found for the Au-STO when compared to the pure STO, as investigated from the degradation of methylene blue solution under ultraviolet and visible light irradiation. The SPSD seems to be a rapid and facile approach to prepare the Au nanoparticles supported on the metal oxide for photocatalytic applications. INTRODUCTION Gold (Au) nanoparticles supported on metal oxide has been received an enormous attention as effective catalysts for the promotion of a wide variety of reactions such as H2 production [1], CO oxidation [2], and oxidative decomposition of organic compounds [3]. Their catalytic properties were strongly dependent on the particle size and shape of Au, amount of Au loading, and Au-support interface interaction as well as metal-oxide support. The SrTiO3 (STO) is selected as support in this study because it is a prominent one due to its thermal stability, chemical inertness, availability, and non-toxicity. Its band gap is also comparable to the conventional TiO2 (Eg ≈ 3.2 eV). Over last decade, several preparation methods have been developed to prepare the Au nanoparticles supported on metal oxide such as depositionprecipitation (DP) [4], photo-deposition (PD) [5], and wet impregnation [6]. These preparation methods commonly use the HAuCl4 as the precursor, which inevitably requires reducing agents (e.g. NaBH4, N2H4, and citric acid) and stabilizers (e.g. thiol compound and polymer) for the particle formation. This may lead to some impurities remaining in the final product. In addition, some limitations were also reported; for example, only half of Au in starting materials could be deposited on supports and the particles size is very sensitive to the concentration of precursor for the DP method. The PD can be applied for only semiconductor support and take a long irradiation time [7,8]. Therefore, a suitable method plays a key role for the preparation of a highly active Au nanoparticles suppo
