Browsing by Author "Fan, Jun"

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C/B codoping effect on band gap narrowing and optical performance of TiO2 photocatalyst: a spin-polarized DFT study
(2013)
Lin, Yanming
;
Jiang, Zhenyi
;
Zhu, Chaoyuan
;
Hu, Xiaoyun
;
Zhang, Xiaodong
The electronic and optical properties of several possible C/B-codoped models of anatase and rutile TiO2 have been investigated systematically using spin-polarized density functional theory calculations. Our calculated results show that the synergistic effect of C/B codoping can induce some hybridized energy states appearing in the forbidden gap and the band gap has a narrowing in anatase and rutile TiO2, which can lead to a decrease of the photon excitation energy and an obvious red-shift of the optical absorption edge. These results lead to an excellent photocatalytic activity in C/B-codoped TiO2. Moreover, with the increase of C and B impurities' concentration in anatase and rutile TiO2, we find that the intensity of impurity states has a strengthening in the band gap, the position of impurity states changes, and the visible-light absorption performance improves gradually.
Electronic and optical performances of Si and Fe-codoped TiO2 nanoparticles: A photocatalyst for the degradation of methylene blue
(2013-10-01)
Lin, Yanming
;
Jiang, Zhenyi
;
Zhu, Chaoyuan
;
Hu, Xiaoyun
;
Zhang, Xiaodong
The effect of substitutional Si, Fe, and Si and Fe (co)doping on the electronic structure and optical properties of anatase and rutile TiO2 have been investigated by the density functional theory. The calculated results indicate that Si doping TiO2 will induce an obvious band gap narrowing by mixing O 2p with Si 3p states, and a series of impurity energy levels (Fe 3d) appear in edge of the VB and the CB through Fe doping. The synergistic effects of Si and Fe codoping can extend optical absorption edge, which leads to higher visible-light photocatalytic activities than pure and monodoped anatase TiO2. Si and Fe-codoped TiO2 nanoparticles was prepared by a sol-gel-solvothermal method, and the photocatalytic activity of TiO2 nanoparticles was examined by measuring the rate of methylene blue decomposition. The experimental results show that Si and Fe-codoped TiO2 sample exhibits better optical absorption performance and higher photocatalytic activities for the degradation of methylene blue than pure and monodoped TiO2, which verifies the reliability of our calculated results. (c) 2013 Elsevier B.V. All rights reserved.
Enhanced optical absorption and photocatalytic activity of anatase TiO2 through (Si,Ni) codoping
(2012-08-06)
Lin, Yanming
;
Jiang, Zhenyi
;
Zhu, Chaoyuan
;
Hu, Xiaoyun
;
Zhang, Xiaodong
The electronic and optical properties of (Si,Ni)-codoped anatase TiO2 are investigated using the density functional theory. The calculated results indicate that the synergistic effects of (Si,Ni) codoping can effectively extend the optical absorption edge, which can lead to higher visible-light photocatalytic activity than pure anatase TiO2. To verify the reliability of our calculated results, nanocrystalline (Si,Ni)-codoped TiO2 is synthesized by a sol-gel-solvothermal method, and experimental results also show that the (Si,Ni)-codoped sample exhibits better absorption performance and higher photocatalytic activities than pure TiO2. 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4745193]
The optical absorption and hydrogen production by water splitting of (Si,Fe)-codoped anatase TiO2 photocatalyst
(2013-05-01)
Lin, Yanming
;
Jiang, Zhenyi
;
Zhu, Chaoyuan
;
Hu, Xiaoyun
;
Zhu, Haiyan
The electronic and optical properties are studied using the density functional theory in (Si,Fe)-codoped anatase TiO2. The calculated results suggest that the synergistic effects of (Si,Fe) codoping can effectively induce the redshift of optical absorption edge, which leads to higher visible-light photocatalytic activity for hydrogen production by water splitting than pure anatase TiO2. To verify the reliability of our calculated results, nanocrystalline (Si,Fe)-codoped TiO2 is synthesized by a sol-gel-solvothermal method, and excellent absorption performance and photocatalytic activity for hydrogen production by water splitting are observed in our experiments. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Visible-light photocatalytic activity of Ni-doped TiO2 from ab initio calculations
(2012-04-16)
Lin, Yan-Ming
;
Jiang, Zhen-Yi
;
Zhu, Chao-Yuan
;
Hu, Xiao-Yun
;
Zhang, Xiao-Dong
The geometrical structures and electronic properties of Ni-doped anatase and rutile TiO2 were successfully calculated and simulated by a plane wave pseudopotential method based on density functional theory (OFT). Our results show that most Ni 3d states are located in the forbidden band of substitutional Ni to O-doped anatase and rutile TiO2, and mix with O 2p states, resulting in a decrease of the photon excitation energy and red-shift of absorption edge compared to pure anatase and rutile. For substitutional Ni to Ti-doped anatase TiO2 under O-rich growth condition, the band gap has a slight decline of about 0.05 eV compared with pure anatase TiO2 and contains a series of impurity energy levels, which may be responsible for the experimental photocatalytic activity and red-shift of absorption edge. (C) 2012 Elsevier B.V. All rights reserved.