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Synthesis and visible-light photocatalytic activity of Bi-doped TiO2 nanobelts
Materials Letters 63 (2009) 2044–2046
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Synthesis and visible-light photocatalytic activity of Bi-doped TiO2 nanobelts Tianhao Ji a,⁎, Fang Yang a, Yuanyuan Lv b, Jiaoyan Zhou b, Jiayue Sun a,⁎ a b
College of Chemical and Environmental Engineering, Beijing Technology and Business University, 48 Fucheng Road, Beijing 100048, China Beijing University of Aeronautics and Astronautics, Beijing 100083, China
a r t i c l e
i n f o
Article history: Received 16 April 2009 Accepted 18 June 2009 Available online 25 June 2009 Keywords: Titania Nanobelts Semiconductors Photocatalyst Hydrothermal synthesis
a b s t r a c t Bi-doped anatase TiO2 nanobelts were synthesized from layer-structural titanate nanobelts using two-step hydrothermal treatment approach. X-ray diffraction (XRD) patterns and transmission electron microscopic (TEM) images show that the doping of Bi3+ cations does not change the crystal structure and morphology of TiO2 nanobelts. The energy-dispersive X-ray (EDX) and inductively coupled plasma-mass spectrometry (ICPMS) analytic results suggest that the doping cations mainly exist near the surface of the TiO2 nanobelts. The ultraviolet-visible (UV–vis) absorption spectra show that the absorption edge for the samples with Bi3+ has red shift as compared with that of undoped TiO2 nanobelts, and correspondingly, the photocatalytic degradation of methylene blue under visible-light illumination is enhanced with the increase of Bi-doping content. © 2009 Elsevier B.V. All rights reserved.
1. Introduction It has been demonstrated that TiO2 is one of the most significant inorganic photocatalytic materials [1]. However, only under the irradiation of ultraviolet rays that it has high photocatalytic activity, and in order to improve visible-light catalytic ability, various modified TiO2 nano-catalysts, such as ion doping, noble metal supported or composite-type, have been widely studied [2–15]. Recently, TiO2 nanopowders modified with Bi-doping ions have been paid attention [5–7], whereas less researchers have ever studied TiO2 nanowires/ nanobelts doped with transition metal cations except for our reports [16,17], and to our knowledge, nobody particularly investigated the preparation and visible-light photocatalytic property of Bi-doped TiO2 nanobelts. As they are separated easily from aqueous solution after they are used, TiO2 nanobelts as visible-light photocatalyst will have potential application in wastewater treatment. Herein, we reported a facile preparation procedure of Bi-doped TiO2 nanobelts and demonstrated that they showed much higher visible-light photocatalytic activity in the photodegradation of methylene blue than that of pure TiO2 nanobelts.
2. Experimental section Bi-doped TiO2 nanobelts were prepared using two-step hydrothermal treatment approach. First of all, layered titanate nanobelts (LTN) were mixed with Bi(NO3)3 glycerol solution with a little bit of distilled water, and the mixture was treated at 120 °C for 35 h. The
⁎ Corresponding authors. Tel.: +86 10 68985545. E-mail addresses: [email protected] (T. Ji), [email protected] (J. Sun). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.06.043
product was immersed in 4 M nitric acid solution for 20 min to take off the Bi species adsorbed on the surface of the LTN, and then, they were washed using glycerol and water for many times by centrifugation. After the washed sample in autoclave was treated at 160 °C for 48 h, the resulting white precipitate was collected by means of filter, washed with deionized water, and dried in air at room temperature. For comparison, the TiO2 nanobelts (TiO2-NBs) without any doping ions have also been prepared. Table 1 shows the reaction condition and actual composition of the prepared Bi-doped TiO2 nanobelts. The as-prepared products were characterized by X-ray powder diffraction (XRD; Rigaku DMAX-PC2200, with Cu Ka radiation (λ = 1.54056 Å)), scanning electron microscopy with EDX analysis (SEM; JEOL-JSM 5800), transmission electron microscope (TEM; JEOL JEM-2010), high-resolution electron microscope (HRTEM; JEOL JEM2010F, with an accelerating voltage of 200 kV), UV–vis absorptive spectra (GBC UV–vis cintra 10e), and inductively coupled plasmamass spectrometry (ICP-MS, Perkin-Elmer, SCIEX ELAN 5000). 3. Results and discussion The XRD patterns of the TiO2-NBs, BTO-01 and BTO-02 are shown in Fig. 1. The patterns indicate that the peaks can be perfectly indexed
Table 1 Bi-to-Ti molar ratios and actual compositions of Bi-doped TiO2 nanowires. Materials (NBs)
Reaction T/t [°C]/[h]
Bi3+:Ti4+ [mol ratio, ICP]
Actual composition
TiO2-NBs BTO-01 BTO-02
160/48 160/48 160/48
0 0.015 0.051
TiO2 Ti0.985Bi0.015O2 Ti0.951Bi0.049O2
T. Ji et al. / Materials Letters 63 (2009) 2044–2046
2045
Fig. 1. XRD patterns of the (a) TiO2 NBs, (b) BTO-01 and (c) BTO-02. Inset is the magnified patterns.
to a pure anatase TiO2 phase, and also indicate that the doping of Bi3+ has not influenced the formation of TiO2 anatase phase. However, the inset shows that the (101) peaks at 25.5° for 2θ shift to low angle much obviously with the increase of Bi content from BTO-01 to BTO02. Such results demonstrate that Bi cations have doped into the crystal structure of TiO2. Because the ionic radius of Bi3+ (0.103 nm) is larger than that of Ti4+ (0.061 nm), the distance of nearest-neighbor crystalline plane becomes wider after Bi3+ ions replace Ti4+ in TiO2. The Bi 4f peaks, centered at 158.0 and 164.0 eV in the XPS spectrum of the BTO-02 recorded at room temperature, support the conclusion and also show the +3 valence state of Bi cations. The Ti 2p double peaks at 458.7 and 464.0 eV demonstrate the +4 valence state of Ti cations in TiO2 (Fig. 2) [18,19]. Fig. 3 shows the SEM, TEM and HRTEM images of the BTO-01 and BTO-02. The arrows in the insets of Fig. 3a and c can demonstrate that
Fig. 2. Bi 4f and Ti 2p XPS spectra of BTO-02 recorded at room temperature.
Fig. 3. SEM, TEM and HRTEM images of the BTO-01 and BTO-02. (a) SEM image of the BTO-01 (scale bar: 1 μm, the inset shows higher magnified SEM image); (b) EDX mapping of the BTO-01; (c) SEM image of the BTO-02 (scale bar: 1 μm, the inset shows higher magnified SEM image); (d) EDX mapping of the BTO-02; (e) TEM image of the BTO-02; and (f) the HRTEM image of the BTO-02.
the nanobelt shape of the BTO-01 and BTO-02 still remained, whereas the surface becomes much rougher. Such rough surface is caused by the phase transformation from layered titanate to anatase TiO2, supported by our published paper for the preparation of Co2+- or Ni2+-doped TiO2 nanobelts [16,17]. In order to know about the doping content of Bi3+, the EDX was performed to measure the BTO-01 and BTO-02 as shown in Fig. 3b and d. The two mappings prove the existence of the elements Bi and Ti, and the molar ratios of Bi to Ti are about 1:31 and 1:9 for the BTO01 and BTO-02, respectively. The measurement value of Bi content is much higher than the ICP-MS analytic results in Table 1, and it indicates that the Bi-doping ions mainly distribute near the surface of TiO2 nanobelts. In addition, the surface and lattice structure of one nanobelt of the BTO-02 were further investigated using TEM and HRTEM techniques (Fig. 3e and f). The rough surface and obvious defects on the lattice structure can be easily observed owing to the Bi3+ substitution, and the 0.35-nm lattice spacing between (101) places, perpendicular to the [101] orientation of the TiO2 nanobelts, can be calculated, which is in good agreement with the strongest (101) peak in the above XRD measurement. To elucidate the effect of Bi-doping ions on optical property of TiO2 NBs, the UV–vis absorption spectra of the TiO2 NBs, BTO-01 and BTO-02 were measured (Fig. 4a). Their maximum absorption is at about 300 nm of wavelength, but indeed Bi doping modifies the absorption characteristics of TiO2 NBs. In comparison with that of the undoped TiO2 NBs, the absorption edges of the BTO-01 and BTO-02 have red shift. The shift means that Bi doping can enlarge the wavelength response range and enhance visible-light photocatalytic activity of TiO2 NBs. Bi doping intrinsically narrows the band-gap transition of TiO2, which has been interpreted in detail in the literature for the photocatalysis of Bi-doped TiO2 nanoparticles [7,19].
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T. Ji et al. / Materials Letters 63 (2009) 2044–2046
surface of TiO2 nanobelts. The visible-light photocatalytic degradation of methylene blue exhibits that Bi-doped samples have higher photodegradation activity than that of TiO2 nanowires. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (No. 20876002), the “973” projects (No. 2006CB932605) and the Beijing Natural Science Foundation (No. 2091002). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.matlet.2009.06.043. References
Fig. 4. (a) UV–vis absorption spectra and (b) visible-light photocatalytic activity of the TiO2 NBs, BTO-01 and BTO-02.
The visible-light photocatalytic activity of the TiO2 NBs, BTO-01 or BTO-02 was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution (Fig. 4b). A mixture of 100 mL 1 × 10- 5 M MB solution and 50 mg of the catalyst in quartz vessel was performed. Prior to visible-light illumination (N420 nm) under 300 W halogen lamp with ultraviolet-filter glass, the mixture needs to be kept in the dark for 30 min under stirring to reach the adsorption equilibrium of MB with the catalyst. A slight decrease of the MB concentration takes place in the presence of the three catalysts before visible-light illumination due to the adsorption of the MB, and with prolonging exposure time, the photodegradation of MB molecules for the BTO-02 is the fastest compared with those for the BTO-01 and TiO2 NBs, and the photocatalytic activity of the BTO-01 is also better than that of the TiO2 NBs. The rapid decrease of the MB concentration is mainly ascribed to the Bi-doping ions into TiO2 NBs, and the increase of Bidoping content obviously enhances the photocatalytic activity. 4. Conclusion Bi-doped anatase TiO2 nanobelts have been synthesized by twostep hydrothermal treatment. The measurement results show that the Bi-doping ions do not change TiO2 anatase phase and nanobelt-like morphology, and also demonstrate that they mainly exist near the
[1] Subramanian V, Wolf E, Kamat PV. Semiconductor-metal composite nanostructures. To what extent do metal nanoparticles improve the photocatalytic activity of TiO2 films? J Phys Chem, B 2001;105:11439–46. [2] Dvoranová D, Brezová V, Mazúr M, Malati MA. Investigations of metal-doped titanium dioxide photocatalysts. Appl Catal, B: Environ 2002;37:91–105. [3] Martin ST, Morrison CL, Hoffmann MR. Photochemical mechanism of sizequantized vanadium-doped TiO2. J Phys Chem 1994;98:13695–704. [4] Jiang HB, Gao L, Zhang QH. Influence of Cu dopants on structure and properties of nanosized TiO2 particulate film. J Inorg Mater 2002;17:787–91. [5] Xu XH, Wang M, Hou Y, Yao WF, Wang D, Wang H. Preparation and characterization of Bi-doped TiO2 photocatalyst. J Mater Sci Lett 2002;21:1655–6. [6] Xin JH, Zhang SM, Qi GD, Zheng XC, Huang WP, Wu SH. Preparation and characterization of the Bi-doped TiO2 photocatalysts. React Kinet Catal Lett 2005;86:291–8. [7] Zuo HS, Sun J, Deng KJ, Su R, Wei FY, Wang DY. Preparation and characterization of Bi3+-TiO2 and its photocatalytic activity. Chem Eng Technol 2007;30:577–82. [8] Yang Y, Wang HY, Li X, Wang C. Electrospun mesoporous W6+-doped TiO2 thin films for efficient visible-light photocatalysis. Mater Lett 2009;63:331–3. [9] Asahi R, Morikawa T, Ohwaki T, Aoki K, Taga Y. Visible-light photocatalysis in nitrogen-doped titanium oxides. Science 2001;293:269–71. [10] Ksibi M, Rossignol S, Tatibouët JM, Trapalis C. Synthesis and solid characterization of nitrogen and sulfur-doped TiO2 photocatalysts active under near visible light. Mater Lett 2008;62:4204–6. [11] Umebayashi T, Yamaki T, Itoh H, Asai K. Band gap narrowing of titanium dioxide by sulfur doping. Appl Phys Lett 2002;81:454–6. [12] Rengaraj S, Li XZ, Tanner PA, Pan ZF, Pang GKH. Photocatalytic degradation of methylparathion-an endocrine disruptor by Bi3+-doped TiO2. J Mol Catal A: Chem 2006;247:36–43. [13] Park MS, Kang M. The preparation of the anatase and rutile forms of Ag-TiO2 and hydrogen production from methanol/water decomposition. Mater Lett 2008;62:183–7. [14] Zou JJ, Chen C, Liu CJ, Zhang YP, Han Y, Cui L. Pt nanoparticles on TiO2 with novel metal-semiconductor interface as highly efficient photocatalyst. Mater Lett 2005;59:3437–40. [15] Ke DN, Liu HJ, Peng TY, Liu X, Dai K. Preparation and photocatalytic activity of WO3/TiO2 nanocomposite particles. Mater Lett 2008;62:447–50. [16] Zhang HY, Ji TH, Liu YF, Cai JW. Preparation and characterization of roomtemperature-ferromagnetic Co-doped anatase TiO2 nanobelts. J Phys Chem C 2008;112:8604–8. [17] Zhang HY, Ji TH, Li LL, Qi XY, Liu YF, Cai JW, et al. Preparation and characterization of room-temperature-ferromagnetic Ni-doped TiO2 nanobelts. Acta Phys -chim Sin 2008;24:601–11. [18] Shi LY, Gu HC, Li CZ, Fang DY, Zhang Y, Hua B. Preparation and properties of SnO2TiO2 composite photocatalysts. Chin J Catal 1999;20:338–42. [19] Lv KL, Zuo HS, Sun J, Deng KJ, Liu SC, Li XF, et al. (Bi, C and N) codoped TiO2 nanoparticles. J Hazard Mater 2009;161:396–401.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Synthesis and visible-light photocatalytic activity of Bi-doped TiO2 nanobelts Tianhao Ji a,⁎, Fang Yang a, Yuanyuan Lv b, Jiaoyan Zhou b, Jiayue Sun a,⁎ a b
College of Chemical and Environmental Engineering, Beijing Technology and Business University, 48 Fucheng Road, Beijing 100048, China Beijing University of Aeronautics and Astronautics, Beijing 100083, China
a r t i c l e
i n f o
Article history: Received 16 April 2009 Accepted 18 June 2009 Available online 25 June 2009 Keywords: Titania Nanobelts Semiconductors Photocatalyst Hydrothermal synthesis
a b s t r a c t Bi-doped anatase TiO2 nanobelts were synthesized from layer-structural titanate nanobelts using two-step hydrothermal treatment approach. X-ray diffraction (XRD) patterns and transmission electron microscopic (TEM) images show that the doping of Bi3+ cations does not change the crystal structure and morphology of TiO2 nanobelts. The energy-dispersive X-ray (EDX) and inductively coupled plasma-mass spectrometry (ICPMS) analytic results suggest that the doping cations mainly exist near the surface of the TiO2 nanobelts. The ultraviolet-visible (UV–vis) absorption spectra show that the absorption edge for the samples with Bi3+ has red shift as compared with that of undoped TiO2 nanobelts, and correspondingly, the photocatalytic degradation of methylene blue under visible-light illumination is enhanced with the increase of Bi-doping content. © 2009 Elsevier B.V. All rights reserved.
1. Introduction It has been demonstrated that TiO2 is one of the most significant inorganic photocatalytic materials [1]. However, only under the irradiation of ultraviolet rays that it has high photocatalytic activity, and in order to improve visible-light catalytic ability, various modified TiO2 nano-catalysts, such as ion doping, noble metal supported or composite-type, have been widely studied [2–15]. Recently, TiO2 nanopowders modified with Bi-doping ions have been paid attention [5–7], whereas less researchers have ever studied TiO2 nanowires/ nanobelts doped with transition metal cations except for our reports [16,17], and to our knowledge, nobody particularly investigated the preparation and visible-light photocatalytic property of Bi-doped TiO2 nanobelts. As they are separated easily from aqueous solution after they are used, TiO2 nanobelts as visible-light photocatalyst will have potential application in wastewater treatment. Herein, we reported a facile preparation procedure of Bi-doped TiO2 nanobelts and demonstrated that they showed much higher visible-light photocatalytic activity in the photodegradation of methylene blue than that of pure TiO2 nanobelts.
2. Experimental section Bi-doped TiO2 nanobelts were prepared using two-step hydrothermal treatment approach. First of all, layered titanate nanobelts (LTN) were mixed with Bi(NO3)3 glycerol solution with a little bit of distilled water, and the mixture was treated at 120 °C for 35 h. The
⁎ Corresponding authors. Tel.: +86 10 68985545. E-mail addresses: [email protected] (T. Ji), [email protected] (J. Sun). 0167-577X/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2009.06.043
product was immersed in 4 M nitric acid solution for 20 min to take off the Bi species adsorbed on the surface of the LTN, and then, they were washed using glycerol and water for many times by centrifugation. After the washed sample in autoclave was treated at 160 °C for 48 h, the resulting white precipitate was collected by means of filter, washed with deionized water, and dried in air at room temperature. For comparison, the TiO2 nanobelts (TiO2-NBs) without any doping ions have also been prepared. Table 1 shows the reaction condition and actual composition of the prepared Bi-doped TiO2 nanobelts. The as-prepared products were characterized by X-ray powder diffraction (XRD; Rigaku DMAX-PC2200, with Cu Ka radiation (λ = 1.54056 Å)), scanning electron microscopy with EDX analysis (SEM; JEOL-JSM 5800), transmission electron microscope (TEM; JEOL JEM-2010), high-resolution electron microscope (HRTEM; JEOL JEM2010F, with an accelerating voltage of 200 kV), UV–vis absorptive spectra (GBC UV–vis cintra 10e), and inductively coupled plasmamass spectrometry (ICP-MS, Perkin-Elmer, SCIEX ELAN 5000). 3. Results and discussion The XRD patterns of the TiO2-NBs, BTO-01 and BTO-02 are shown in Fig. 1. The patterns indicate that the peaks can be perfectly indexed
Table 1 Bi-to-Ti molar ratios and actual compositions of Bi-doped TiO2 nanowires. Materials (NBs)
Reaction T/t [°C]/[h]
Bi3+:Ti4+ [mol ratio, ICP]
Actual composition
TiO2-NBs BTO-01 BTO-02
160/48 160/48 160/48
0 0.015 0.051
TiO2 Ti0.985Bi0.015O2 Ti0.951Bi0.049O2
T. Ji et al. / Materials Letters 63 (2009) 2044–2046
2045
Fig. 1. XRD patterns of the (a) TiO2 NBs, (b) BTO-01 and (c) BTO-02. Inset is the magnified patterns.
to a pure anatase TiO2 phase, and also indicate that the doping of Bi3+ has not influenced the formation of TiO2 anatase phase. However, the inset shows that the (101) peaks at 25.5° for 2θ shift to low angle much obviously with the increase of Bi content from BTO-01 to BTO02. Such results demonstrate that Bi cations have doped into the crystal structure of TiO2. Because the ionic radius of Bi3+ (0.103 nm) is larger than that of Ti4+ (0.061 nm), the distance of nearest-neighbor crystalline plane becomes wider after Bi3+ ions replace Ti4+ in TiO2. The Bi 4f peaks, centered at 158.0 and 164.0 eV in the XPS spectrum of the BTO-02 recorded at room temperature, support the conclusion and also show the +3 valence state of Bi cations. The Ti 2p double peaks at 458.7 and 464.0 eV demonstrate the +4 valence state of Ti cations in TiO2 (Fig. 2) [18,19]. Fig. 3 shows the SEM, TEM and HRTEM images of the BTO-01 and BTO-02. The arrows in the insets of Fig. 3a and c can demonstrate that
Fig. 2. Bi 4f and Ti 2p XPS spectra of BTO-02 recorded at room temperature.
Fig. 3. SEM, TEM and HRTEM images of the BTO-01 and BTO-02. (a) SEM image of the BTO-01 (scale bar: 1 μm, the inset shows higher magnified SEM image); (b) EDX mapping of the BTO-01; (c) SEM image of the BTO-02 (scale bar: 1 μm, the inset shows higher magnified SEM image); (d) EDX mapping of the BTO-02; (e) TEM image of the BTO-02; and (f) the HRTEM image of the BTO-02.
the nanobelt shape of the BTO-01 and BTO-02 still remained, whereas the surface becomes much rougher. Such rough surface is caused by the phase transformation from layered titanate to anatase TiO2, supported by our published paper for the preparation of Co2+- or Ni2+-doped TiO2 nanobelts [16,17]. In order to know about the doping content of Bi3+, the EDX was performed to measure the BTO-01 and BTO-02 as shown in Fig. 3b and d. The two mappings prove the existence of the elements Bi and Ti, and the molar ratios of Bi to Ti are about 1:31 and 1:9 for the BTO01 and BTO-02, respectively. The measurement value of Bi content is much higher than the ICP-MS analytic results in Table 1, and it indicates that the Bi-doping ions mainly distribute near the surface of TiO2 nanobelts. In addition, the surface and lattice structure of one nanobelt of the BTO-02 were further investigated using TEM and HRTEM techniques (Fig. 3e and f). The rough surface and obvious defects on the lattice structure can be easily observed owing to the Bi3+ substitution, and the 0.35-nm lattice spacing between (101) places, perpendicular to the [101] orientation of the TiO2 nanobelts, can be calculated, which is in good agreement with the strongest (101) peak in the above XRD measurement. To elucidate the effect of Bi-doping ions on optical property of TiO2 NBs, the UV–vis absorption spectra of the TiO2 NBs, BTO-01 and BTO-02 were measured (Fig. 4a). Their maximum absorption is at about 300 nm of wavelength, but indeed Bi doping modifies the absorption characteristics of TiO2 NBs. In comparison with that of the undoped TiO2 NBs, the absorption edges of the BTO-01 and BTO-02 have red shift. The shift means that Bi doping can enlarge the wavelength response range and enhance visible-light photocatalytic activity of TiO2 NBs. Bi doping intrinsically narrows the band-gap transition of TiO2, which has been interpreted in detail in the literature for the photocatalysis of Bi-doped TiO2 nanoparticles [7,19].
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T. Ji et al. / Materials Letters 63 (2009) 2044–2046
surface of TiO2 nanobelts. The visible-light photocatalytic degradation of methylene blue exhibits that Bi-doped samples have higher photodegradation activity than that of TiO2 nanowires. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (No. 20876002), the “973” projects (No. 2006CB932605) and the Beijing Natural Science Foundation (No. 2091002). Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.matlet.2009.06.043. References
Fig. 4. (a) UV–vis absorption spectra and (b) visible-light photocatalytic activity of the TiO2 NBs, BTO-01 and BTO-02.
The visible-light photocatalytic activity of the TiO2 NBs, BTO-01 or BTO-02 was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution (Fig. 4b). A mixture of 100 mL 1 × 10- 5 M MB solution and 50 mg of the catalyst in quartz vessel was performed. Prior to visible-light illumination (N420 nm) under 300 W halogen lamp with ultraviolet-filter glass, the mixture needs to be kept in the dark for 30 min under stirring to reach the adsorption equilibrium of MB with the catalyst. A slight decrease of the MB concentration takes place in the presence of the three catalysts before visible-light illumination due to the adsorption of the MB, and with prolonging exposure time, the photodegradation of MB molecules for the BTO-02 is the fastest compared with those for the BTO-01 and TiO2 NBs, and the photocatalytic activity of the BTO-01 is also better than that of the TiO2 NBs. The rapid decrease of the MB concentration is mainly ascribed to the Bi-doping ions into TiO2 NBs, and the increase of Bidoping content obviously enhances the photocatalytic activity. 4. Conclusion Bi-doped anatase TiO2 nanobelts have been synthesized by twostep hydrothermal treatment. The measurement results show that the Bi-doping ions do not change TiO2 anatase phase and nanobelt-like morphology, and also demonstrate that they mainly exist near the
[1] Subramanian V, Wolf E, Kamat PV. Semiconductor-metal composite nanostructures. To what extent do metal nanoparticles improve the photocatalytic activity of TiO2 films? J Phys Chem, B 2001;105:11439–46. [2] Dvoranová D, Brezová V, Mazúr M, Malati MA. Investigations of metal-doped titanium dioxide photocatalysts. Appl Catal, B: Environ 2002;37:91–105. [3] Martin ST, Morrison CL, Hoffmann MR. Photochemical mechanism of sizequantized vanadium-doped TiO2. J Phys Chem 1994;98:13695–704. [4] Jiang HB, Gao L, Zhang QH. Influence of Cu dopants on structure and properties of nanosized TiO2 particulate film. J Inorg Mater 2002;17:787–91. [5] Xu XH, Wang M, Hou Y, Yao WF, Wang D, Wang H. Preparation and characterization of Bi-doped TiO2 photocatalyst. J Mater Sci Lett 2002;21:1655–6. [6] Xin JH, Zhang SM, Qi GD, Zheng XC, Huang WP, Wu SH. Preparation and characterization of the Bi-doped TiO2 photocatalysts. React Kinet Catal Lett 2005;86:291–8. [7] Zuo HS, Sun J, Deng KJ, Su R, Wei FY, Wang DY. Preparation and characterization of Bi3+-TiO2 and its photocatalytic activity. Chem Eng Technol 2007;30:577–82. [8] Yang Y, Wang HY, Li X, Wang C. Electrospun mesoporous W6+-doped TiO2 thin films for efficient visible-light photocatalysis. Mater Lett 2009;63:331–3. [9] Asahi R, Morikawa T, Ohwaki T, Aoki K, Taga Y. Visible-light photocatalysis in nitrogen-doped titanium oxides. Science 2001;293:269–71. [10] Ksibi M, Rossignol S, Tatibouët JM, Trapalis C. Synthesis and solid characterization of nitrogen and sulfur-doped TiO2 photocatalysts active under near visible light. Mater Lett 2008;62:4204–6. [11] Umebayashi T, Yamaki T, Itoh H, Asai K. Band gap narrowing of titanium dioxide by sulfur doping. Appl Phys Lett 2002;81:454–6. [12] Rengaraj S, Li XZ, Tanner PA, Pan ZF, Pang GKH. Photocatalytic degradation of methylparathion-an endocrine disruptor by Bi3+-doped TiO2. J Mol Catal A: Chem 2006;247:36–43. [13] Park MS, Kang M. The preparation of the anatase and rutile forms of Ag-TiO2 and hydrogen production from methanol/water decomposition. Mater Lett 2008;62:183–7. [14] Zou JJ, Chen C, Liu CJ, Zhang YP, Han Y, Cui L. Pt nanoparticles on TiO2 with novel metal-semiconductor interface as highly efficient photocatalyst. Mater Lett 2005;59:3437–40. [15] Ke DN, Liu HJ, Peng TY, Liu X, Dai K. Preparation and photocatalytic activity of WO3/TiO2 nanocomposite particles. Mater Lett 2008;62:447–50. [16] Zhang HY, Ji TH, Liu YF, Cai JW. Preparation and characterization of roomtemperature-ferromagnetic Co-doped anatase TiO2 nanobelts. J Phys Chem C 2008;112:8604–8. [17] Zhang HY, Ji TH, Li LL, Qi XY, Liu YF, Cai JW, et al. Preparation and characterization of room-temperature-ferromagnetic Ni-doped TiO2 nanobelts. Acta Phys -chim Sin 2008;24:601–11. [18] Shi LY, Gu HC, Li CZ, Fang DY, Zhang Y, Hua B. Preparation and properties of SnO2TiO2 composite photocatalysts. Chin J Catal 1999;20:338–42. [19] Lv KL, Zuo HS, Sun J, Deng KJ, Liu SC, Li XF, et al. (Bi, C and N) codoped TiO2 nanoparticles. J Hazard Mater 2009;161:396–401.