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Title: Ab initio studies of Nb–N–S tri-doped TiO{sub 2} with enhanced visible light photocatalytic activity

Abstract

The electronic and optical properties of Nb–N–S tri-doped anatase TiO{sub 2} were investigated within the frame of the density functional theory (DFT) plus U method. Results show that a significant red-shift effect and improvement of visible-light absorption for Nb–N–S tri-doped TiO{sub 2} are observed with respect to pure TiO{sub 2} and S–N codoped TiO{sub 2}. At the same time, the enhanced visible-light photocatalytic activity of tri-doped TiO{sub 2} is derived from the narrowing band gap, the appearance of Nb 4d state at the bottom of conduction band and the mixture of N 2p, S 3p states forming new defect levels at the top of valance band, which is excellently consistent with the previous experiment. Moreover, S ion leads to the lattice distortion and promotes the visible-light photocatalytic activity. Furthermore, the absorbance of 1.39NbNS–TiO{sub 2} accords well with the experimental result in the visible region. It is also found that the 2.78NbNS–TiO{sub 2} can be easily grown under O-rich condition and have the strongest absorbance from 2.0 to 4.2 eV among four models.

Authors:
;  [1];  [1];  [2]
  1. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22584107
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 238; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; COMPUTER CALCULATIONS; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ELECTRONIC STRUCTURE; MIXTURES; NIOBIUM COMPOUNDS; NITROGEN COMPOUNDS; OPTICAL PROPERTIES; PHOTOCATALYSIS; SULFUR COMPOUNDS; TITANIUM OXIDES

Citation Formats

Ren, Dahua, Cheng, Junxia, Cheng, Xinlu, E-mail: chengxl@scu.edu.cn, and Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064. Ab initio studies of Nb–N–S tri-doped TiO{sub 2} with enhanced visible light photocatalytic activity. United States: N. p., 2016. Web. doi:10.1016/J.JSSC.2016.03.020.
Ren, Dahua, Cheng, Junxia, Cheng, Xinlu, E-mail: chengxl@scu.edu.cn, & Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064. Ab initio studies of Nb–N–S tri-doped TiO{sub 2} with enhanced visible light photocatalytic activity. United States. doi:10.1016/J.JSSC.2016.03.020.
Ren, Dahua, Cheng, Junxia, Cheng, Xinlu, E-mail: chengxl@scu.edu.cn, and Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064. Wed . "Ab initio studies of Nb–N–S tri-doped TiO{sub 2} with enhanced visible light photocatalytic activity". United States. doi:10.1016/J.JSSC.2016.03.020.
@article{osti_22584107,
title = {Ab initio studies of Nb–N–S tri-doped TiO{sub 2} with enhanced visible light photocatalytic activity},
author = {Ren, Dahua and Cheng, Junxia and Cheng, Xinlu, E-mail: chengxl@scu.edu.cn and Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064},
abstractNote = {The electronic and optical properties of Nb–N–S tri-doped anatase TiO{sub 2} were investigated within the frame of the density functional theory (DFT) plus U method. Results show that a significant red-shift effect and improvement of visible-light absorption for Nb–N–S tri-doped TiO{sub 2} are observed with respect to pure TiO{sub 2} and S–N codoped TiO{sub 2}. At the same time, the enhanced visible-light photocatalytic activity of tri-doped TiO{sub 2} is derived from the narrowing band gap, the appearance of Nb 4d state at the bottom of conduction band and the mixture of N 2p, S 3p states forming new defect levels at the top of valance band, which is excellently consistent with the previous experiment. Moreover, S ion leads to the lattice distortion and promotes the visible-light photocatalytic activity. Furthermore, the absorbance of 1.39NbNS–TiO{sub 2} accords well with the experimental result in the visible region. It is also found that the 2.78NbNS–TiO{sub 2} can be easily grown under O-rich condition and have the strongest absorbance from 2.0 to 4.2 eV among four models.},
doi = {10.1016/J.JSSC.2016.03.020},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 238,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}
  • Graphical abstract: FeNS-TiO{sub 2} exhibits stronger SPS response than that of pure TiO{sub 2}, indicating that the FeNS-TiO{sub 2} should have a higher separation rates of photoinduced charge carriers. Further, for the sample FeNS-TiO{sub 2} a broad shoulder SPS response can be seen at the wavelength range from 390 to 550 nm, suggesting that the light absorption in visible region of FeNS-TiO{sub 2} was greatly improved, which is beneficial to the enhancement of photocatalytic activity. Display Omitted Highlights: ► FeNS-TiO{sub 2} catalyst has been synthesized in the presence of ammonium ferrous sulfate. ► The light absorption edge of FeNS-TiO{sub 2}more » catalyst was red-shifted to visible region. ► The separation efficiency of photoinduced charge carriers of FeNS-TiO{sub 2} was improved. ► The activity enhanced mechanism of FeNS-TiO{sub 2} was discussed in detail. -- Abstract: Fe–N–S-tridoped TiO{sub 2} was synthesized through simple one step sol–gel reactions in the presence of ammonium ferrous sulfate. The resulting materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance spectrum and surface photovoltage spectroscopy. Results revealed that Fe and S were incorporated into the lattice of TiO{sub 2} by substituting for some Ti atoms and N for O atoms in the lattice of TiO{sub 2}. Tri-doping with Fe, N and S could inhibit the phase transformation of TiO{sub 2} from anatase to rutile, restrain the growth of crystallite sizes, extended the light absorption into the visible region and separate photoinduced charge carriers. The visible photocatalytic activity of Fe–N–S-tridoped TiO{sub 2} was higher than that of N-TiO{sub 2} and P25 TiO{sub 2}. The enhanced photocatalytic activity was attributed to the small crystallite size, high crystallinity, the intense light absorption in visible region, narrow band gap and high separation efficiency of photoinduced charge carriers.« less
  • The density of states and optical properties of N, S, and (N, S)-doped anatase TiO{sub 2} are calculated based on the density functional theory. The results indicate that the doping S atoms occupy the Ti-atom sites in anatase TiO{sub 2} lattice. The mixing of O 2p, N 2p, S 3p, and Ti 3d states in the forbidden gap of (N, S)-codoped TiO{sub 2} can result in the higher visible-light photocatalytic activities than those monodoped TiO{sub 2}. For comparison, (N, S)-codoped TiO{sub 2} was also synthesized by one-step hydrothermal method, and the optical absorption spectra obtained by experiments verified the reliabilitymore » of our calculation.« less
  • A one-step low-temperature hydrothermal route was developed for the synthesis of S-doped TiO{sub 2} photocatalysts from TiS{sub 2} and HCl. Crystalline TiO{sub 2} was formed and sulfur could be efficiently doped into the anatase lattice under hydrothermal conditions. When the initial TiS{sub 2} concentration is increased, the content of S-dopant and optical absorption in the visible region also increase. The photocatalytic activity of the S-doped TiO{sub 2} was evaluated through the degradation of 4-chlorophenol under visible light irradiation. Our results show that the S-doped TiO{sub 2} prepared by this hydrothermal approach possesses much higher photocatalytic activity than that obtained bymore » the traditional high-temperature thermal annealing method.« less
  • The effect of electronegative difference between nitrogen and oxygen on electronic properties of N-doped anatase TiO{sub 2} has been studied using first-principles calculations. The results indicate that the valence band maximum (VBM) shifts to high energy by 0.27 eV and the band gap states composed of N 2p, O 2p, and Ti 3d states are formed through the three states entering into the gap after N doping. The interactions of three states widen and delocalize the band gap states. The raised VBM and the wide band gap states can improve the visible light photocatalytic activity.
  • Highlights: ► Novel synthesis of C-N co-doped TiO{sub 2}. ► Self-assembly of C-N co-doped TiO{sub 2} nanorods by nanoparticles. ► Excellent photocatalytic efficiency. -- Abstract: The C-N co-doped TiO{sub 2} nanorods were synthesized by the vapor transport method of water molecules, and urea was used as the carbon and nitrogen source. The samples were characterized by X-ray diffraction and photoelectron spectroscopy analysis. The scanning electron microscope images showed that as-prepared TiO{sub 2} powders were nanorods, which were formed by the stacking of nanoparticles with a uniform size around 40 nm. The degradation of methylene blue with the prepared nanorods demonstratedmore » the photocatalytic activities of TiO{sub 2} under visible light are improved by doping with C and N elements. The main reasons were discussed: doping with C and N elements could enhance the corresponding visible-light absorption of TiO{sub 2}. On the other hand, doping C and N could create more oxygen vacancies in the TiO{sub 2} crystals, which could capture the photogenerated electrons more effectively. Thus, more photogenerated holes could be left to improve the photocatalytic activity of TiO{sub 2}.« less