Journal of Colloid and Interface Science 418 (2014) 317–323
Contents lists available at ScienceDirect
Journal of Colloid and Interface Science www.elsevier.com/locate/jcis
Growth of BiOBr nanosheets on C3N4 nanosheets to construct two-dimensional nanojunctions with enhanced photoreactivity for NO removal Yanjuan Sun a,b, Wendong Zhang c, Ting Xiong a, Zaiwang Zhao a, Fan Dong a,b,⇑, Ruiqi Wang a, Wing-Kei Ho d a Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067, China b Chongqing Key Laboratory for Urban Atmospheric Environment Integrated Observation & Pollution Prevention and Control, Environmental Monitoring Center of Chongqing, Chongqing 401147, China c College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045, China d Department of Science and Environmental Studies, The Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Hong Kong, China
a r t i c l e
i n f o
Article history: Received 28 September 2013 Accepted 12 December 2013 Available online 22 December 2013 Keywords: BiOBr nanosheets C3N4 nanosheets Two-dimensional nanojunctions Visible light photocatalytic NO removal
a b s t r a c t The development of approaches to effectively separate the photo-induced charge carriers is a key strategy to promote the photocatalytic activity of semiconductor photocatalysts. This work represents the construction of novel two-dimensional (2D) BiOBr/C3N4 nanojunctions by the growth of BiOBr nanosheets on the surface of C3N4 nanosheets at room temperature. The samples were characterized by XRD, FT-IR, TEM, UV–vis DRS and PL. The photocatalytic activity of the samples was evaluated by the removal of NO in air under visible light irradiation. The results indicated that electronic coupling took place between the {0 0 1} plane of BiOBr and {0 0 2} plane of C3N4. The BiOBr/C3N4 nanojunctions exhibited enhanced visible light photocatalytic activity compared with pure BiOBr and C3N4. The enhanced photoactivity can be mainly ascribed to the efficient separation and transportation of photo-induced electrons and holes due to the well-coupled crystal planes and well-matched band structures. The present work could provide new insights into the design and construction of 2D nanojunctions with well-matched crystal planes and band structures for efficient visible light photocatalysis. Ó 2013 Elsevier Inc. All rights reserved.
1. Introduction Photocatalysis, as a green technology, is attracting considerable interests due to its great potential in solving global environmental and energy problems [1–7]. TiO2 is the first investigated and earthabundant photocatalyst, which works only with ultraviolet ( 420 nm).
In the present work, the photocatalytic performance of the assynthesized samples was evaluated by removal of NO in gas phase in order to demonstrate their intrinsic activity under visible light irradiation. Fig. 9a shows the variation in NO concentration (C/C0 %) with irradiation time over the samples under visible light irradiation (k > 420 nm). Here, C0 is the initial concentration of NO, and C is the concentration of NO after photocatalytic reaction for time t. In the presence of the as-synthesized photocatalytic materials, the NO reacted with the photo-generated reactive radicals and produced HNO2 and HNO3, which were involved four reactions as displayed in Eqs. (1)-(4) [14,38,48].
NO þ 2 OH ! NO2 þ H2 O
ð1Þ
NO2 þ OH ! NO3 þ Hþ
ð2Þ
NO þ NO2 þ H2 O ! 2HNO2
ð3Þ
NO þ O2 ! NO3
ð4Þ
characterization results revealed that the coupling of BiOBr {0 0 1} plane with C3N4 {0 0 2} plane led to strong electronic interaction between the two components with well-matched band structures. The photocatalytic activity of BiOBr/C3N4 nanojunctions was significantly enhanced for the removal of NO in air under visible light irradiation, which can be ascribed to the highly efficient separation of photo-induced charges at the interface of nanojunctions. The present work demonstrated that novel 2D nanojunctioned visible light photocatalysts with efficient activity can be constructed by combining two visible light active 2D semiconductors with well-coupled crystal planes and well-matched band structure, which could provide a new approach for promoting the activity of current photocatalysts.
Acknowledgments
Fig. 9a shows that the NO concentration for all samples decreased rapidly in 5 min. However, the gradual generation of reaction intermediates and final products may occupy the active sites of photocatalysts, which results in the slight decrease in activity during 5–15 min. When the reaction reached equilibrium, the activity was kept constant. After 30 min irradiation, the NO removal ratios of BiOBr, C3N4 and BiOBr/C3N4 are 21.2%, 22.9% and 32.7%, respectively. The rate constant of BiOBr/C3N4 is 0.115 min1, which is 1.5 and 2.0 times higher than those of pure C3N4 (0.078 min1) and BiOBr (0.059 min1), respectively. The enhancement of photocatalytic activity of BiOBr/C3N4 nanojunctions could be ascribed to the following factors. First, the well-coupled crystal planes, well-matched band structure and layered 2D nanojunctions are favorable for the separation and transfer of the photo-induced electrons and holes. Second, the combination of 2D nanosheets increased the surface areas of BiOBr/C3N4 (22 m2/g), which is larger than that of pure C3N4 (14 m2/g) and BiOBr (11 m2/g). The large surface areas could facilitate mass transfer and provide more activity sites for the photochemical reaction. Our work could provide a new perspective for design of 2D nanojunctioned photocatalysts with well-coupled crystal planes and well-matched band structure by combining two visible light active semiconductors with 2D nanostructure. 4. Conclusion In summary, two-dimensional nanojunctions were constructed by self-assembly of BiOBr nanosheets on C3N4 nanosheets by a chemical precipitation method at room temperature. Various
This research was financially supported by the National Natural Science Foundation of China (51108487), the Science and Technology Project from Chongqing Education Commission (KJ130725), the project from Innovative Team for Environmental pollution Control of CTBU, the Natural Science Foundation Project of CQ CSTC (cstc2013jcyjA20018, cstc2013yykfB50008), the Innovative Research Team Development Program in University of Chongqing (KJTD201314) and the Opening Project of Key Laboratory of Green Catalysis of Sichuan Institutes of High Education (LZJ1204).
References [1] S.W. Liu, J.G. Yu, M. Jaroniec, Chem. Mater. 23 (2011) 4085. [2] A. Di Paola, E. García-López, G. Marcì, L. Palmisano, J. Hazard. Mater. 211–212 (2012) 3. [3] F. Dong, Z. Wang, Y. Sun, W.H. Zhang, J. Colloid Interface Sci. 401 (2013) 70. [4] Q.J. Xiang, J.G. Yu, P.K. Wong, J. Colloid Interface Sci. 357 (2011) 163. [5] M.A. Rauf, S.S. Ashraf, Chem. Eng. J. 151 (2009) 10. [6] Z. Liu, B. Wu, Y. Zhu, F. Wang, L. Wang, J. Colloid Interface Sci. 392 (2013) 337. [7] Q.J. Xiang, J.G. Yu, Chem. Soc. Rev. 41 (2012) 782. [8] L.G. Devi, R. Kavitha, Appl. Catal. B 140–141 (2013) 559. [9] G. Liu, L. Wang, H. Yang, H. Cheng, G.Q. Lu, J. Mater. Chem. 20 (2010) 831. [10] F. Dong, H.Q. Wang, Z.B. Wu, J.F. Qiu, J. Colloid Interface Sci. 343 (2010) 200. [11] H. Tong, S. Ouyang, Y. Bi, N. Umezawa, M. Oshikiri, J.H. Ye, Adv. Mater. 24 (2012) 229. [12] Y. Zheng, J. Liu, J. Liang, M. Jaroniec, S. Qiao, Energy Environ. Sci. 5 (2012) 6717. [13] Y. Wang, X. Wang, M. Antonietti, Angew. Chem., Int. Ed. 51 (2012) 68. [14] W.D. Zhang, Q. Zhang, F. Dong, Ind. Eng. Chem. Res. 52 (2013) 6740. [15] S. Guo, X.F. Li, H.Q. Wang, F. Dong, Z.B. Wu, J. Colloid Interface Sci. 369 (2012) 373. [16] D.S. Wang, Y.D. Duan, Q.Z. Luo, X.Y. Li, L.L. Bao, Desalination 270 (2011) 174. [17] H. Yuzawa, T. Yoshida, H. Yoshida, Appl. Catal. B 115–116 (2012) 294. [18] P. Wang, B.B. Huang, X.Y. Zhang, X.Y. Qin, Y. Dai, Z.Y. Wang, Z.Z. Lou, ChemCatChem 3 (2011) 360. [19] J.S. Zhang, J.H. Sun, K. Maeda, K. Domen, P. Liu, M. Antonietti, X.Z. Fu, X.C. Wang, Energy Environ. Sci. 4 (2011) 675. [20] F. Dong, H.T. Liu, W.K. Ho, M. Fu, Z.B. Wu, Chem. Eng. J. 214 (2013) 198.
Y. Sun et al. / Journal of Colloid and Interface Science 418 (2014) 317–323 [21] F. Dong, L.W. Wu, Y.J. Sun, M. Fu, Z.B. Wu, S.C. Lee, J. Mater. Chem. 21 (2011) 15171. [22] G. Liu, P. Niu, H.M. Cheng, ChemPhysChem 14 (2013) 885. [23] X.C. Wang, S. Blechert, M. Antonietti, ACS Catal. 2 (2012) 1596. [24] Z.Z. Lin, X.C. Wang, Angew. Chem., Int. Ed. 52 (2013) 1735. [25] H. Xu, J. Yan, Y.G. Xu, Y.H. Song, H.M. Li, J.X. Xia, C.J. Huang, H.L. Wan, Appl. Catal. B 129 (2013) 182. [26] B. Kiskan, J.S. Zhang, X.C. Wang, M. Antonietti, Y. Yagci, ACS Macro. Lett. 1 (2012) 546. [27] X.H. Li, X.C. Wang, Chem. Sci. 3 (2012) 2170. [28] Q.J. Xiang, J.G. Yu, M. Jaroniec, J. Phys. Chem. C 115 (2011) 7355. [29] Y.D. Hou, A.B. Laursen, J.S. Zhang, G.G. Zhang, Y.S. Zhu, X.C. Wang, S. Dahl, I. Chorkendorff, Angew. Chem., Int. Ed. 52 (2013) 1. [30] Y.J. Cui, Z.X. Ding, X.Z. Fu, X.C. Wang, Angew. Chem., Int. Ed. 51 (2012) 11814. [31] H.J. Yan, H.X. Yang, J. Alloys, Compounds 509 (2011) 26. [32] S.C. Yan, S.B. Lv, Z.S. Li, Z.G. Zou, Dalton Trans. 39 (2010) 1488. [33] J.X. Sun, Y.P. Yuan, L.G. Qiu, X.J.A.J. Xie, Y.H. Shen, J.F. Zhu, Dalton Trans. 41 (2012) 6756.
323
[34] Y.J. Wang, X.J. Bai, C.S. Pan, J. He, Y.F. Zhu, J. Mater. Chem. 22 (2012) 11568. [35] H.W. Kang, S.N. Lim, D.S. Song, S.B. Park, Int. J. Hydrogen Energy 37 (2012) 11602. [36] J. Fu, B.B. Chang, Y.L. Tian, F.N. Xi, X.P. Dong, J. Mater. Chem. A 1 (2013) 3083. [37] L. Huang, H. Xu, Y. Li, X. Cheng, J. Xia, G. Cai, Dalton Trans. 42 (2013) 8606. [38] F. Dong, Y.J. Sun, M. Fu, Z.B. Wu, S.C. Lee, J. Hazard. Mater. 219–220 (2012) 26. [39] Y. Ham, K. Maeda, D. Cha, K. Takanabe, K. Domen, Chem. Asian J. 8 (2013) 218. [40] Z.H. Ai, W.K. Ho, S.C. Lee, L.Z. Zhang, Environ. Sci. Technol. 43 (2009) 4143. [41] F. Dong, Y.J. Sun, L.W. Wu, M. Fu, Z.B. Wu, Sci. Technol. 2 (2012) 1332. [42] Y.J. Chen, M. Wen, Q.S. Wu, CrystEngComm 13 (2011) 3035. [43] Z.H. Ai, W.K. Ho, S.C. Lee, J. Phys. Chem. C 115 (2011) 25330. [44] J. Jiang, K. Zhao, X.Y. Xiao, L.Z. Zhang, J. Am. Chem. Soc. 134 (2012) 4473. [45] F. Dong, W.R. Zhao, Z.B. Wu, S. Guo, J. Hazard. Mater. 162 (2009) 763. [46] Y. Yuan, S. Cao, Y. Liao, L. Yin, C. Xue, Appl. Catal. B 140–141 (2013) 164. [47] J. Fu, Y.L. Tian, B.B. Chang, F.N. Xi, X.P. Dong, J. Mater. Chem. 22 (2012) 21159. [48] H.T. Tian, J.W. Li, M. Ge, Y.P. Zhao, L. Liu, Sci. Technol. 2 (2012) 2351.
Contents lists available at ScienceDirect
Journal of Colloid and Interface Science www.elsevier.com/locate/jcis
Growth of BiOBr nanosheets on C3N4 nanosheets to construct two-dimensional nanojunctions with enhanced photoreactivity for NO removal Yanjuan Sun a,b, Wendong Zhang c, Ting Xiong a, Zaiwang Zhao a, Fan Dong a,b,⇑, Ruiqi Wang a, Wing-Kei Ho d a Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067, China b Chongqing Key Laboratory for Urban Atmospheric Environment Integrated Observation & Pollution Prevention and Control, Environmental Monitoring Center of Chongqing, Chongqing 401147, China c College of Urban Construction and Environmental Engineering, Chongqing University, Chongqing 400045, China d Department of Science and Environmental Studies, The Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Hong Kong, China
a r t i c l e
i n f o
Article history: Received 28 September 2013 Accepted 12 December 2013 Available online 22 December 2013 Keywords: BiOBr nanosheets C3N4 nanosheets Two-dimensional nanojunctions Visible light photocatalytic NO removal
a b s t r a c t The development of approaches to effectively separate the photo-induced charge carriers is a key strategy to promote the photocatalytic activity of semiconductor photocatalysts. This work represents the construction of novel two-dimensional (2D) BiOBr/C3N4 nanojunctions by the growth of BiOBr nanosheets on the surface of C3N4 nanosheets at room temperature. The samples were characterized by XRD, FT-IR, TEM, UV–vis DRS and PL. The photocatalytic activity of the samples was evaluated by the removal of NO in air under visible light irradiation. The results indicated that electronic coupling took place between the {0 0 1} plane of BiOBr and {0 0 2} plane of C3N4. The BiOBr/C3N4 nanojunctions exhibited enhanced visible light photocatalytic activity compared with pure BiOBr and C3N4. The enhanced photoactivity can be mainly ascribed to the efficient separation and transportation of photo-induced electrons and holes due to the well-coupled crystal planes and well-matched band structures. The present work could provide new insights into the design and construction of 2D nanojunctions with well-matched crystal planes and band structures for efficient visible light photocatalysis. Ó 2013 Elsevier Inc. All rights reserved.
1. Introduction Photocatalysis, as a green technology, is attracting considerable interests due to its great potential in solving global environmental and energy problems [1–7]. TiO2 is the first investigated and earthabundant photocatalyst, which works only with ultraviolet ( 420 nm).
In the present work, the photocatalytic performance of the assynthesized samples was evaluated by removal of NO in gas phase in order to demonstrate their intrinsic activity under visible light irradiation. Fig. 9a shows the variation in NO concentration (C/C0 %) with irradiation time over the samples under visible light irradiation (k > 420 nm). Here, C0 is the initial concentration of NO, and C is the concentration of NO after photocatalytic reaction for time t. In the presence of the as-synthesized photocatalytic materials, the NO reacted with the photo-generated reactive radicals and produced HNO2 and HNO3, which were involved four reactions as displayed in Eqs. (1)-(4) [14,38,48].
NO þ 2 OH ! NO2 þ H2 O
ð1Þ
NO2 þ OH ! NO3 þ Hþ
ð2Þ
NO þ NO2 þ H2 O ! 2HNO2
ð3Þ
NO þ O2 ! NO3
ð4Þ
characterization results revealed that the coupling of BiOBr {0 0 1} plane with C3N4 {0 0 2} plane led to strong electronic interaction between the two components with well-matched band structures. The photocatalytic activity of BiOBr/C3N4 nanojunctions was significantly enhanced for the removal of NO in air under visible light irradiation, which can be ascribed to the highly efficient separation of photo-induced charges at the interface of nanojunctions. The present work demonstrated that novel 2D nanojunctioned visible light photocatalysts with efficient activity can be constructed by combining two visible light active 2D semiconductors with well-coupled crystal planes and well-matched band structure, which could provide a new approach for promoting the activity of current photocatalysts.
Acknowledgments
Fig. 9a shows that the NO concentration for all samples decreased rapidly in 5 min. However, the gradual generation of reaction intermediates and final products may occupy the active sites of photocatalysts, which results in the slight decrease in activity during 5–15 min. When the reaction reached equilibrium, the activity was kept constant. After 30 min irradiation, the NO removal ratios of BiOBr, C3N4 and BiOBr/C3N4 are 21.2%, 22.9% and 32.7%, respectively. The rate constant of BiOBr/C3N4 is 0.115 min1, which is 1.5 and 2.0 times higher than those of pure C3N4 (0.078 min1) and BiOBr (0.059 min1), respectively. The enhancement of photocatalytic activity of BiOBr/C3N4 nanojunctions could be ascribed to the following factors. First, the well-coupled crystal planes, well-matched band structure and layered 2D nanojunctions are favorable for the separation and transfer of the photo-induced electrons and holes. Second, the combination of 2D nanosheets increased the surface areas of BiOBr/C3N4 (22 m2/g), which is larger than that of pure C3N4 (14 m2/g) and BiOBr (11 m2/g). The large surface areas could facilitate mass transfer and provide more activity sites for the photochemical reaction. Our work could provide a new perspective for design of 2D nanojunctioned photocatalysts with well-coupled crystal planes and well-matched band structure by combining two visible light active semiconductors with 2D nanostructure. 4. Conclusion In summary, two-dimensional nanojunctions were constructed by self-assembly of BiOBr nanosheets on C3N4 nanosheets by a chemical precipitation method at room temperature. Various
This research was financially supported by the National Natural Science Foundation of China (51108487), the Science and Technology Project from Chongqing Education Commission (KJ130725), the project from Innovative Team for Environmental pollution Control of CTBU, the Natural Science Foundation Project of CQ CSTC (cstc2013jcyjA20018, cstc2013yykfB50008), the Innovative Research Team Development Program in University of Chongqing (KJTD201314) and the Opening Project of Key Laboratory of Green Catalysis of Sichuan Institutes of High Education (LZJ1204).
References [1] S.W. Liu, J.G. Yu, M. Jaroniec, Chem. Mater. 23 (2011) 4085. [2] A. Di Paola, E. García-López, G. Marcì, L. Palmisano, J. Hazard. Mater. 211–212 (2012) 3. [3] F. Dong, Z. Wang, Y. Sun, W.H. Zhang, J. Colloid Interface Sci. 401 (2013) 70. [4] Q.J. Xiang, J.G. Yu, P.K. Wong, J. Colloid Interface Sci. 357 (2011) 163. [5] M.A. Rauf, S.S. Ashraf, Chem. Eng. J. 151 (2009) 10. [6] Z. Liu, B. Wu, Y. Zhu, F. Wang, L. Wang, J. Colloid Interface Sci. 392 (2013) 337. [7] Q.J. Xiang, J.G. Yu, Chem. Soc. Rev. 41 (2012) 782. [8] L.G. Devi, R. Kavitha, Appl. Catal. B 140–141 (2013) 559. [9] G. Liu, L. Wang, H. Yang, H. Cheng, G.Q. Lu, J. Mater. Chem. 20 (2010) 831. [10] F. Dong, H.Q. Wang, Z.B. Wu, J.F. Qiu, J. Colloid Interface Sci. 343 (2010) 200. [11] H. Tong, S. Ouyang, Y. Bi, N. Umezawa, M. Oshikiri, J.H. Ye, Adv. Mater. 24 (2012) 229. [12] Y. Zheng, J. Liu, J. Liang, M. Jaroniec, S. Qiao, Energy Environ. Sci. 5 (2012) 6717. [13] Y. Wang, X. Wang, M. Antonietti, Angew. Chem., Int. Ed. 51 (2012) 68. [14] W.D. Zhang, Q. Zhang, F. Dong, Ind. Eng. Chem. Res. 52 (2013) 6740. [15] S. Guo, X.F. Li, H.Q. Wang, F. Dong, Z.B. Wu, J. Colloid Interface Sci. 369 (2012) 373. [16] D.S. Wang, Y.D. Duan, Q.Z. Luo, X.Y. Li, L.L. Bao, Desalination 270 (2011) 174. [17] H. Yuzawa, T. Yoshida, H. Yoshida, Appl. Catal. B 115–116 (2012) 294. [18] P. Wang, B.B. Huang, X.Y. Zhang, X.Y. Qin, Y. Dai, Z.Y. Wang, Z.Z. Lou, ChemCatChem 3 (2011) 360. [19] J.S. Zhang, J.H. Sun, K. Maeda, K. Domen, P. Liu, M. Antonietti, X.Z. Fu, X.C. Wang, Energy Environ. Sci. 4 (2011) 675. [20] F. Dong, H.T. Liu, W.K. Ho, M. Fu, Z.B. Wu, Chem. Eng. J. 214 (2013) 198.
Y. Sun et al. / Journal of Colloid and Interface Science 418 (2014) 317–323 [21] F. Dong, L.W. Wu, Y.J. Sun, M. Fu, Z.B. Wu, S.C. Lee, J. Mater. Chem. 21 (2011) 15171. [22] G. Liu, P. Niu, H.M. Cheng, ChemPhysChem 14 (2013) 885. [23] X.C. Wang, S. Blechert, M. Antonietti, ACS Catal. 2 (2012) 1596. [24] Z.Z. Lin, X.C. Wang, Angew. Chem., Int. Ed. 52 (2013) 1735. [25] H. Xu, J. Yan, Y.G. Xu, Y.H. Song, H.M. Li, J.X. Xia, C.J. Huang, H.L. Wan, Appl. Catal. B 129 (2013) 182. [26] B. Kiskan, J.S. Zhang, X.C. Wang, M. Antonietti, Y. Yagci, ACS Macro. Lett. 1 (2012) 546. [27] X.H. Li, X.C. Wang, Chem. Sci. 3 (2012) 2170. [28] Q.J. Xiang, J.G. Yu, M. Jaroniec, J. Phys. Chem. C 115 (2011) 7355. [29] Y.D. Hou, A.B. Laursen, J.S. Zhang, G.G. Zhang, Y.S. Zhu, X.C. Wang, S. Dahl, I. Chorkendorff, Angew. Chem., Int. Ed. 52 (2013) 1. [30] Y.J. Cui, Z.X. Ding, X.Z. Fu, X.C. Wang, Angew. Chem., Int. Ed. 51 (2012) 11814. [31] H.J. Yan, H.X. Yang, J. Alloys, Compounds 509 (2011) 26. [32] S.C. Yan, S.B. Lv, Z.S. Li, Z.G. Zou, Dalton Trans. 39 (2010) 1488. [33] J.X. Sun, Y.P. Yuan, L.G. Qiu, X.J.A.J. Xie, Y.H. Shen, J.F. Zhu, Dalton Trans. 41 (2012) 6756.
323
[34] Y.J. Wang, X.J. Bai, C.S. Pan, J. He, Y.F. Zhu, J. Mater. Chem. 22 (2012) 11568. [35] H.W. Kang, S.N. Lim, D.S. Song, S.B. Park, Int. J. Hydrogen Energy 37 (2012) 11602. [36] J. Fu, B.B. Chang, Y.L. Tian, F.N. Xi, X.P. Dong, J. Mater. Chem. A 1 (2013) 3083. [37] L. Huang, H. Xu, Y. Li, X. Cheng, J. Xia, G. Cai, Dalton Trans. 42 (2013) 8606. [38] F. Dong, Y.J. Sun, M. Fu, Z.B. Wu, S.C. Lee, J. Hazard. Mater. 219–220 (2012) 26. [39] Y. Ham, K. Maeda, D. Cha, K. Takanabe, K. Domen, Chem. Asian J. 8 (2013) 218. [40] Z.H. Ai, W.K. Ho, S.C. Lee, L.Z. Zhang, Environ. Sci. Technol. 43 (2009) 4143. [41] F. Dong, Y.J. Sun, L.W. Wu, M. Fu, Z.B. Wu, Sci. Technol. 2 (2012) 1332. [42] Y.J. Chen, M. Wen, Q.S. Wu, CrystEngComm 13 (2011) 3035. [43] Z.H. Ai, W.K. Ho, S.C. Lee, J. Phys. Chem. C 115 (2011) 25330. [44] J. Jiang, K. Zhao, X.Y. Xiao, L.Z. Zhang, J. Am. Chem. Soc. 134 (2012) 4473. [45] F. Dong, W.R. Zhao, Z.B. Wu, S. Guo, J. Hazard. Mater. 162 (2009) 763. [46] Y. Yuan, S. Cao, Y. Liao, L. Yin, C. Xue, Appl. Catal. B 140–141 (2013) 164. [47] J. Fu, Y.L. Tian, B.B. Chang, F.N. Xi, X.P. Dong, J. Mater. Chem. 22 (2012) 21159. [48] H.T. Tian, J.W. Li, M. Ge, Y.P. Zhao, L. Liu, Sci. Technol. 2 (2012) 2351.
