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在密度泛函理论的基础上，系统地研究了Cu/N（共）掺杂的TiO2/MoS2异质结体系的几何结构、电子结构和光学性质.计算发现，TiO2/MoS2异质结的带隙相比于纯的TiO2（101）表面明显变小，Cu/N（共）掺杂TiO2/MoS2异质结体系的禁带宽度也明显地减小，这导致光子激发能量的降低和光吸收能力的提高.通过计算Cu/N（共）掺杂TiO2/MoS2的差分电荷密度，发现光生电子与空穴积累在掺杂后的TiO2（101）表面和单层MoS2之间，这表明掺杂杂质体系可以有效地抑制光生电子-空穴对的复合.此外，我们计算了在不同压力下TiO2/MoS2异质结的几何、电子和光学性质，发现适当增加压力可以有效提高异质结的光吸收性能.本文结果表明，Cu/N（共）掺杂TiO2/MoS2异质结和对TiO2/MoS2异质结加压都能有效地提高材料的光学性能.Anatase titanium dioxide (TiO2) has attracted much attention due to its excellent photocatalytic properties. However, the band gap of anatase TiO2 is 3.2 eV, which can absorb only about 4% of the ultraviolet light (λ < 400 nm). Molybdenum disulfide (MoS2) is a new layered two-dimensional compound semiconductor, and it has been widely studied for its preferably optical absorption and photocatalytic properties. Moreover, the high recombination rate of photoexcited electron-hole of monolayer MoS2 leads to low photocatalytic efficiency. In this work, based on Heyd-Scuseria-Ernzerhof (HSE06) hybrid density functional theory, the geometric structure, electronic structure, optical properties, charge transfer and effect of pressure on structure of Cu/N doped TiO2/MoS2 heterostructures are systematically studied. The interface interaction between anatase TiO2(101) surface and monolayer MoS2 shows that TiO2 and MoS2 form a van der Waals heterostructure. The defect formation energy is calculated to demonstrate that Cu@O&N@O is the most stable codoping site. The result of the density of states shows that the band gap of TiO2/MoS2 heterojunction is 1.38 eV, which is obviously smaller than that of the pure anatase TiO2(101) surface (2.90 eV). The band gap of Cu/N doped TiO2/MoS2 heterojunction obviously decreases, and an impurity band provided by Cu 3d orbitals appears in the forbidden band, which leads to the decrease of the photon excitation energy and the enhancement of the optical absorption capacity. The x-y planar averaged and three-dimensional charge density difference of Cu/N doped TiO2/MoS2 are also calculated. It is found that there are electrons' and holes' accumulation in the doped anatase TiO2(101) surface and the single layer MoS2, showing that the Cu/N doping can effectively reduce the recombination of the photoexcited electron hole pairs. Calculated optical absorption spectra show that Cu/N doped TiO2/MoS2 system has obvious improvement in the absorption of visible light. In addition, we calculate the geometrical, electronic and optical absorption spectra of TiO2/MoS2 heterojunction under different pressures. The results show that the appropriate increase of pressure can effectively improve the optical absorption properties of heterojunction and Cu/N doped TiO2/MoS2 heterojunction and TiO2/MoS2 heterojunction can effectively improve the optical properties of the material. These findings are helpful in understanding the photocatalytic mechanism and relevant experimental observations.
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Keywords:
- hybrid functionals /
- electronic structures /
- doping /
- optical properties
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[1] Kwon W W, Han H, Kim J H 2017 Energy 103 226
[2] Rahmouni S, Negrou B, Settou N, Dominguez J, Gouareh A 2017 Energy 42 1383
[3] Lewis N S, Nocera D G 2006 Science 103 15729
[4] Fujishima A, Honda K 1972 Nature 238 37
[5] Ishikawa A, Takata T, Kondo J N, Hara M, Kobayashi H, Domen K 2002 J. Am. Chem. Soc. 124 13547
[6] Maeda K, Takata T, Hara M, Saito N, Inoue Y, Kobayashi H, Domen K 2005 J. Am. Chem. Soc. 127 8286
[7] Maeda K, Teramura K, Lu D, Takata T, Saito N, Inoue Y, Domen K 2006 Nature 440 295
[8] Lee Y, Terashima H, Shimodaira Y, Teramura K, Hara M, Kobayashi H, Domen K, Yashima M 2007 J. Phys. Chem. C 111 1042
[9] Chen X, Mao S S 2007 Chem. Rev. 107 289
[10] Khan S U M, Al-Shahry M, Ingler Jr W B 2002 Science 297 2243
[11] Yin S, Zhang Q, Saito F, Sato T 2003 Chem. Lett. 32 358
[12] Ohtani B, Handa J I, Nishimoto S I, Kagiya T 1985 Chem. Phys. Lett. 120 292
[13] Elsellami L, Dappozze F, Fessi N, Houas A, Guillard C 2018 Process. Saf. Environ. 113 109
[14] Jung H S, Kim H 2009 Electron. Mater. Lett. 5 73
[15] Tehare K K, Bhande S S, Mutkule S U, Stadler F J, Ao J P, Mane R S, Liu X 2017 J. Alloys Compd. 704 187
[16] Meng A, Zhang J, Xu D, Cheng B, Yu J 2016 Appl. Catal. B 198 286
[17] Cheng X, Yu X, Xing Z, Yang L 2016 Arab. J. Chem. 9 1706
[18] Wang W K, Chen J J, Gao M, Huang Y X, Zhang X, Yu H Q 2016 Appl. Catal. B: Environ. 195 69
[19] Xu C, Zhang Y, Chen J, Lin J, Zhang X, Wang Z, Zhou J 2017 Appl. Catal. B: Environ. 204 324
[20] Zhang W, Yin J, Tang X, Zhang P, Ding Y 2017 Physica 85 259
[21] Brindha A, Sivakumar T 2017 J. Photoch. Photobio. A: Chem. 340 14
[22] Ren D, Li H, Cheng X 2015 Solid. State. Commun. 223 54
[23] Kalantari K, Kalbasi M, Sohrabi M, Royaee S J 2017 Ceram. Int. 43 973
[24] Yan J, Wu H, Chen H, Zhang Y, Zhang F, Liu S F 2016 Appl. Catal. B: Environ. 191 130
[25] Jaiswal R, Bharambe J, Patel N, Dashora A, Kothari D C, Miotello A 2015 Appl. Catal. B: Environ. 168 333
[26] Sun L, Xian Z, Cheng X 2012 Langmuir 28 5882
[27] Yang C T, Balakrishnan N, Bhethanabotla V R 2017 J. Phys. Chem. C 118 4702
[28] He H, Lin J, Fu W, Wang X, Wang H 2016 Adv. Energy Mater. 6 1600464
[29] Tao J G, Chai J W, Guan L X, Pan J S, Wang S J 2015 Appl. Phys. Lett. 106 081602
[30] Zhang J, Huang L, Lu Z, Jin Z, Wang X 2016 J. Alloys Compd. 688 840
[31] Yang X, Huang H, Jin B, Luo J, Zhou X 2016 RSC. Adv. 6 107075
[32] Yuan Y J, Ye Z J, Lu H, Hu B, Li Y H, Chen D, Zhong J S, Yu Z T, Zou Z 2016 ACS Catal. 6 532
[33] Liu X, Xing Z, Zhang Y, Li Z, Wu X, Tan S, Yu X, Zhu Q, Zhou W 2017 Appl. Catal. B: Environ. 201 119
[34] Kresse G, Hafner J 1994 Phys. Rev. B 49 14251
[35] Perdew J P, Wang Y 1992 Phys. Rev. B 45 13244
[36] Zhao S, Xue J, Kang W 2014 J. Chem. Phys. Lett. 595 35
[37] Zhang J J, Gao B, Dong S 2016 Phys. Rev. B 93 155430
[38] Shirley R, Kraft M, Inderwildi O R 2010 Phys. Rev. B 81 075111
[39] Zhang J F, Zhou P, Liu J J, Yu J G 2014 Chem. Chem. Phys. 16 20382
[40] Ataca C, Sahin H 2012 J. Phys. Chem. C 116 8983
[41] Burdett J K, Hughbanks T, Miller G J, Richardson J W, Smith J V 1987 J. Am. Chem. Soc. 109 3639
[42] Tahir M, Tahir B 2016 Appl. Surf. Sci. 377 244
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