Efficient visible-light-driven photocatalytic H 2 production over Cr/N-codoped SrTiO 3 He Yu a,c , Shicheng Yan a,b, *, Zhaosheng Li a,b , Tao Yu a,c , Zhigang Zou a,b,c, * a National Laboratory of Solid State Microstructure, Nanjing University, 210093, PR China b Eco-materials and Renewable Energy Research Center (ERERC), College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, PR China c Department of Physics, Nanjing University, 210093, PR China article info Article history: Received 13 March 2012 Received in revised form 14 May 2012 Accepted 18 May 2012 Available online 12 July 2012 Keywords: Photocatalysis SrTiO 3 Visible light response Water splitting abstract Visible-light-response Cr/N-codoped SrTiO 3 was prepared by a solegel hydrothermal method. The comparison studies indicate that Cr-doped and Cr/N-codoped SrTiO 3 can be synthesized by this means, but not the N-doped SrTiO 3 . The theoretical calculations exhibit the defect formation energy of the Cr/N codoping into SrTiO 3 is much smaller than that of the N doping into SrTiO 3 , illuminating that the incorporation of Cr can promote the N doping into the O sites in the SrTiO 3 . Compared to the Cr-doped SrTiO 3 , the Cr/N-codoped SrTiO 3 photocatalyst shows the high photocatalytic activities for hydrogen production with the quantum efficiency of 3.1% at 420 nm, due to the smaller band gap and much less vacancy defects. Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction Hydrogen, as an environmentally friendly fuel, is attracting more and more attention. Since the production of hydrogen through photoinduced water splitting on titanium oxide was discovered [1], semiconductor-based photocatalysis has prompted many investigations, because this technique makes use of abundant, long lasting and clean solar energy. In order to construct an efficient photocatalytic water splitting reac- tion, some photocatalytic materials, such as oxides, oxy- nitrides and sulfides, have been explored [2]. To apply the photocatalysis technique, an ideal photocatalyst is expected to be having good photostability, having a narrow band gap to achieve the efficient use of solar energy, and having highly efficiency in separating, collecting and transporting charges for the chemical processes. SrTiO 3 is a promising perovskite-type photocatalyst for water decomposition. However, SrTiO 3 has a wide band gap of 3.2 eV, only responds to ultraviolet light, which accounts for only 4% of the incoming solar energy. Element doping usually is an efficient route to broaden the light absorption of the wide-band-gap semiconductors into the visible light region, which possesses 43% of the solar energy. To obtain the visible light response, doping with foreign elements into SrTiO 3 has been studied by many research groups [3e7]. Some three- valence metal ions, such as Rh 3þ , Ir 3þ and Ru 3þ , were incor- porated into the Ti 4þ sites of SrTiO 3 . The strong hybridization of orbital of the doping elements with the O 2p states leads to * Corresponding authors. National Laboratory of Solid State Microstructure, Nanjing University, 210093, PR China. Tel.: þ86 25 83686630; fax: þ86 25 83686632. E-mail addresses: yscfei@nju.edu.cn (S. Yan), zgzou@nju.edu.cn (Z. Zou). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 37 (2012) 12120 e12127 0360-3199/$ e see front matter Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2012.05.097