In Situ Ti 3+ /N-Codoped Three-Dimensional (3D) Urchinlike Black TiO 2 Architectures as Efficient Visible-Light-Driven Photocatalysts Jiaojiao Jiang, † Zipeng Xing,* ,† Meng Li, † Zhenzi Li, ‡ Xiaoyan Wu, ‡ Mengqiao Hu, † Jiafeng Wan, † Nan Wang,* ,§ Alexey Sergeevich Besov, ∥,⊥ and Wei Zhou* ,† † Department of Environmental Science, School of Chemistry and Materials Science, Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People’s Republic of China, Heilongjiang University, Harbin 150080, People’s Republic of China ‡ Department of Epidemiology and Biostatistics, Harbin Medical University, Harbin 150086, People’s Republic of China § Jiyang College, Zhejiang A&F University, Zhuji 311800, People’s Republic of China ∥ Boreskov Institute of Catalysis, Pr. Ak. Lavrentyeva 5, Novosibirsk 630090, Russia ⊥ Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia * S Supporting Information ABSTRACT: In situ Ti 3+ /N-codoped 3D urchinlike black TiO 2 (b- N-TiO 2 ) is synthesized via hydrothermal treatment with an in situ solid-state chemical reduction method, followed by annealing at 350 °C in argon. The results indicate that N and Ti 3+ was codoped into the lattice of anatase TiO 2 . The prepared b-N-TiO 2 , with a narrow bandgap of ∼2.43 eV, possesses a three-dimensional (3D) urchinlike nanostructure, which is composed of fiberlike architecture with a length of 200−400 nm and a width of 25 nm. The visible-light-driven photocatalytic degradation rate of Methyl Orange and hydrogen evolution rate for b-N-TiO 2 are 95.2% and 178 μmol h −1 g −1 , respectively, which are ∼3 and ∼8 times higher than those of pristine TiO 2 . The excellent photocatalytic activity is mainly attributed to synergistic effect of the N and Ti 3+ codoping narrowing the bandgap, and unique 3D urchinlike architecture favors the separation and transport of photogenerated charge carriers and offers more surface-active sites. 1. INTRODUCTION Nowadays, the global environmental pollution becomes more and more serious, and the global energy crisis and other environmental problems must be solved urgently. 1−3 It has been well-established that titanium dioxide (TiO 2 ) is an intriguing semiconductor photocatalyst, because of the advantages of innocuity, green environmental protection, low price, chemical inertness, and the ability to degrade toxic and organic pollutants. 4,5 It has been widely used in many applications, such as dye-sensitized solar cells, 6−8 Li-ion batteries, 9−11 pollutant degradation, 12,13 and H 2 evolution. 14,15 Unfortunately, TiO 2 with a wide band gap of 3.2 eV can only absorb ultraviolet (UV) and possesses rapid recombination rate of photogenerated electron−hole pairs, which severely limit its practical application and overall efficiency under sunlight. 16 Because the UV in the solar spectrum is <5%, it is important to improve the photoresponse of TiO 2 to the visible-light region. 17 In order to enhance the photoresponse of TiO 2 to the visible- light region, various methods have been proposed, such as surface sensitization, semiconductor composites fabrication, doping, and surface complexation. 18,19 Among the various methods, doping with other elements including metal, nonmetal, and self-doping, as a feasible and simple method, 20,21 has been widely used for TiO 2 modification to enhance the photocatalytic activity. Especially, nonmetal element doping, such as N, S, C, and halogen atoms, is considered to be an effective method to enlarge the photoresponse of TiO 2 . Among them, nitrogen doping has been widely studied, because of the significant effect for improving visible-light photocatalytic activity. 22 Nitrogen doping contributes to reducing the band gap of TiO 2 by introducing N atoms into the TiO 2 lattice, which can generate an overlap of N 2p states and O 2p states on the top of the valence band (VB) of TiO 2 . 23 Thus, the photocatalytic activity of TiO 2 is obviously improved. In the report by Li et al. regarding nitrogen- doped mesoporous TiO 2 spheres, the as-prepared samples successfully reduced the band gap and enhanced photocatalytic activity, because of the incorproation of N atoms into the lattice of TiO 2 . 24 L. Gomathi Devi et al. proposed a review on modified N-TiO 2 for green energy applications under UV/visible light. 25 Received: April 22, 2017 Revised: June 20, 2017 Accepted: June 21, 2017 Article pubs.acs.org/IECR © XXXX American Chemical Society A DOI: 10.1021/acs.iecr.7b01693 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX