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Ionic liquid-assisted hydrothermal synthesis of square BiOBr nanoplates with highly efficient photocatalytic activity
Materials Letters 118 (2014) 154–157
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Ionic liquid-assisted hydrothermal synthesis of square BiOBr nanoplates with highly efficient photocatalytic activity Danjun Mao, Xiaomeng Lü, Zhifeng Jiang, Jimin Xie n, Xiufeng Lu, Wei Wei, A.M. Showkot Hossain School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 15 October 2013 Accepted 11 December 2013 Available online 18 December 2013
The square BiOBr nanoplates were successfully synthesized under hydrothermal conditions with the ionic liquids used as solvent, reactant and the directing agent. The prepared BiOBr nanoplates were characterized by XRD, TEM, HRTEM, SAED, EDX, and DRS, which showed that the square BiOBr nanoplates possessed pure tetragonal BiOBr phase with high-ratio exposure of {001} facets. It was found that the ionic liquid played a key role in the formation of square BiOBr nanoplates and the possible growth mechanism was also discussed. According to the results in the photodegradation of Rhodamine B under visible-light irradiation, the square BiOBr nanoplates exhibited excellent photocatalytic activity. & 2013 Elsevier B.V. All rights reserved.
Keywords: BiOBr Square nanoplate Crystal structure Solar energy materials
1. Introduction BiOBr, as one of the important V–VII group compound semiconductors, has attracted considerable attention recently because of its unique and excellent electrical, magnetic, optical, and luminescent properties, in addition to be a new visible light responding photocatalyst [1–4]. Bismuth oxybromide prefers to crystallize in the tetragonal matlockite structure, a layer structure characterized by [Bi2O2] slabs interleaved by double slabs of halogen atoms [5,6]. Inspired by the unique properties and promising photocatalytical applications, many research groups have carried out studies on BiOBr micro/nanostructures. Up to now, a variety of BiOBr micro/ nanostructures, including nanoplates, nanobelts and microspheres, have been synthesized with various approaches [7–9]. However, the fabrication of 2D BiOBr nanostructures with uniform and well defined shapes is still hard to obtain and highly desired. Compared to the conventional organic solvents, the ionic liquids (ILs) can be used as template, solvent and reactor in the synthesis of inorganic materials for its unique properties such as extremely low volatility, high ionic conductivity, good dissolving ability, designable structures, and a large electrochemical window [10–12]. Xia demonstrated the EG-assisted solvothermal synthesis of BiOBr microspheres in the presence of ionic liquid [13]. Zhang et al. reported the hierarchical BiOBr microspheres synthesized by using the ionothermal method at 200 1C [14]. However, to the best of our knowledge, the utilization of ionic liquids, a versatile and
n
Corresponding author. Tel.: þ 86 511 88791708; fax: þ 86 511 88791800. E-mail address: [email protected] (J. Xie).
0167-577X/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2013.12.049
environmental medium, in the controlled synthesis of 2D BiOBr nanostructures has not yet been reported. Herein, for the first time, we report a facile and environmentally benign green route to synthesize square BiOBr nanoplates with exposed {001} facets via an ionic liquid-assisted hydrothermal process. In the reaction, ionic liquids were used not only as solvent and reactant, but also as a directing agent in the formation of square BiOBr nanoplates with exposed {001} facets. Moreover, the visible-light-driven photocatalytic activity of the as-obtained BiOBr materials was investigated for the degradation of Rhodamine B (RhB).
2. Experimental section In a typical procedure, 0.97 g of Bi(NO3)3 5H2O was first dissolved in 2 mL of a 2 M nitric acid solution and then it was diluted to 5 mL with deionized water. 0.80 g of [Bmim]Br or 0.43 g of KBr was added slowly into 30 mL of deionized water. Thereafter, a yellow homogeneous solution was obtained when the Bi (NO3)3 5H2O solution was added dropwise into the above solution. After that, 4 mL of NaOH solution (2.0 mol L 1) was slowly added into the mixed solution. The samples denoted as IL-BiOBr and K-BiOBr represent the samples prepared in the presence of [Bmin]Br and KBr, respectively. The solution was stirred for 15 min and transferred to a 50 mL Teflon-lined autoclave, which was placed at 120 1C in an oven for 12 h, and then cooled to room temperature. The product was collected by filtration and washed with deionized water and ethanol for several times, and dried in vacuum at 60 1C overnight.
D. Mao et al. / Materials Letters 118 (2014) 154–157
155
3. Results and discussion
The phase purity and crystal structure of the products were determined by X-ray diffractometer (Bruker AXS Company, Karlsruhe, Germany). Transmission electron microscopy (TEM, JEM-2010, JEOL), high-resolution TEM (HRTEM) and selected area electron diffraction (SAED) were measured at an accelerating voltage of 200 kV. The photocatalytic activities of the samples were evaluated by degradation of Rhodamine B (RhB) in an aqueous solution under visible-light. A 300 W Xe lamp was used as the light source with a 420 nm cutoff filter to provide visible-light irradiation. The photocatalyst (50 mg) was poured in RhB aqueous solution (100 mL, 10 mg L 1) in a Pyrex reactor at room temperature under air. Before illumination, the solution was stirred in the dark for 60 min in order to reach the adsorption–desorption equilibrium of RhB on the photocatalysts. The concentrations of RhB were monitored with a UV–vis spectrophotometer in terms of the absorbance at 553 nm during the photodegradation process.
The morphology and structure of the samples were revealed by TEM, HRTEM images and SAED patterns. As shown in Fig. 1(a,b), the IL-BiOBr nanoplates are square and nanoplate geometric shapes. It was also clearly observed that the IL-BiOBr nanoplates were 120–270 nm in width and 20–35 nm in thickness. The SAED pattern of an individual IL-BiOBr nanoplate (Fig. 1c) shows the clear electron diffraction (ED) spots with well alignment, indicating the single-crystal nature of the nanoplate. The angle labeled in the SAED pattern is 451, which is in good agreement with the theoretical value of the angle between the (110) and (200) planes. The set of diffraction spots can be indexed as the [001] zone axis of tetragonal BiOBr. HRTEM image of IL-BiOBr (Fig. 1d) revealed the highly crystalline nature of the nanoplates. The clear lattice fringes with an interplanar lattice spacing of 0.269 nm correspond to the
110 200 45 110
0.269nm Fig. 1. TEM (a,b), SAED patterns (c) and HRTEM (d) images of the IL-BiOBr square nanoplates. TEM (e,f) images of the K-BiOBr nanosheets.
400
intensity (a.u.)
(105)
(204) (220) (006) (214) (106) (310) (116)
(004) (200) (113) (104) (211) (114) (212)
IL-BiOBr
(112)
intensity (a.u.)
(101)
(003)
(002)
(110)
(001)
(102)
500
Bi Br
300
200
K-BiOBr 100
O Br
standard spectrum
Bi
0 10
20
30
40
50
2 (degree)
60
70
80
1
2
3
4
5
6
7
Energy(keV)
Fig. 2. (a) XRD patterns of the BiOBr samples and (b) EDX spectrum of the IL-BiOBr square nanoplates.
8
9
10
11
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D. Mao et al. / Materials Letters 118 (2014) 154–157
(003) atomic planes. As shown in Fig. 1(e,f), the TEM images showed that the K-BiOBr sample is composed of irregular nanosheets with widths of 0.5–2.0 μm. The phase and composition of as-prepared samples were examined using powder XRD measurements. As shown in Fig. 2a, all the peaks can be indexed to the tetragonal phase BiOBr with lattice constants of a¼b¼3.926 Å and c¼8.103 Å (JCPDS Card no. 09-0393). No other phases were detected. The peak intensities for the K-BiOBr sample highly match the standard spectrum, which is shown in the bottom of Fig. 2a. As for the IL-BiOBr sample, a great increase on the relative intensity of (001) series peaks can be found, which is labeled with “▼” in the figure. Typically, the intensity ratio of the (001) to (102) peak is 0.98, obviously larger than the standard value of 0.4, indicating that the crystal has special anisotropic growth along the (001) plane, in good agreement with the HRTEM and SAED results. Based on the above results and the symmetries of tetragonal BiOBr, the preponderant growth direction of square BiOBr nanoplates was the [001] orientation. In addition, the energy-dispersive X-ray (EDX) spectrum of the IL-BiOBr sample (Fig. 2b) also reveals that the atomic ratio of Bi/Br in the sample is approximately equal to 1:1, which is consistent with the XRD results. The ionic liquids played a vital role in the formation of the square BiOBr nanoplates with exposed {001} facets. It is believed
2.0
0.8
Absorbance (a.u.)
1.5
1.0
0.6
0.5
0.0
0.4
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
that the surface energy of the facets can be reduced by compensating the surface charge with a passivating reagent such as an ionic liquid [15]. Due to the strong electrostatic interactions between the ions of the ionic liquid and the O-terminated (001) facets of BiOBr [16], the surface energies of the (001) facets may decrease greatly in comparison to those of other crystal faces, resulting in a relatively slow growth rate for the (001) facets. Thus the (001) facets may appear as exposed facet, as in the square structure. The UV–vis diffuse-reflectance spectrum reveals that the absorption edge of the IL-BiOBr square nanoplates extended to the visible-light region, which indicates the possibility of high photocatalytic activity of these materials under visible-light irradiation (Fig. 3). The absorption onset of the square nanoplate is at ca. 445 nm, corresponding to a band-gap energy of about 2.62 eV, which is consistent with previous studies (2.75 eV) [6]. We evaluated photocatalytic activities of the as-prepared IL-BiOBr and K-BiOBr samples by degradation of RhB and compared them with P25. The results in Fig. 4(a) indicate that IL-BiOBr exhibits excellent performance in terms of both adsorption and degradation of RhB. The intensity of RhB at its main absorbance peak diminishes sharply to 43.5% of its original value in the dark, and almost totally disappears in 90 min under visible-light. However, the K-BiOBr sample shows a poor adsorption amount of 23.3% and also a poor degradation amount of 65.7% after 90 min visible-light irradiation. Such a significant improvement in efficiency of IL-BiOBr samples was mainly attributed to its higher adsorption capacity by high-ratio exposure of {001} facets and higher separation efficiency of photogenerated carriers due to the self-built electric field [17]. Thus, the square BiOBr nanoplates with exposed {001} facets show highly efficient photocatalytic activity to RhB under visible-light.
4.0
0.2
4. Conclusion
0.0 200
300
400
500
600
700
800
Wavelength (nm) Fig. 3. UV–vis diffusion reflectance spectra of the IL-BiOBr square nanoplates. Inset: curves of (αhν)1/2 vs. photon energy.
In summary, square BiOBr nanoplates with exposed {001} facets have been successfully synthesized via an ionic liquidassisted hydrothermal approach. The possible formation mechanism is discussed. The resulting BiOBr square nanoplates exhibited excellent visible-light-driven photocatalytic activity. This work not only provides a new route to fabricate 2D BiOBr nanostructures, but also facilitate the reasonable design and performance enhancement of photocatalysts.
1.0
RhB photodegradation (C/Co)
Absorbance (a.u.)
0.8
0 min 15 min 30 min 45 min 60 min 75 min 90 min
0.6
0.4
0.2
0.0 200
300
400
500
600
Wavelength / nm
700
blank RhB
1.0
IL-BiOBr
800
P25
0.8 0.6
K-BiOBr
0.4 0.2 0.0 -60
light on
0
IL-BiOBr
15
30
45
60
75
90
Irradiation time / min
Fig. 4. (a) UV–vis absorption spectral and (b) the photodegradation efficiency of the photodegradation of RhB under visible-light irradiation (λ Z420 nm).
D. Mao et al. / Materials Letters 118 (2014) 154–157
Acknowledgments This work was supported by the National Natural Science Foundation of China (Grant No. 21003065) and Natural Science Foundation of Jiangsu Province (BK2010044). References [1] [2] [3] [4] [5]
Deng ZT, Chen D, Peng B, Tang FQ. Cryst Growth Des 2008;8:29953003. Zhang X, Ai ZH, Jia FL, Zhang LZJ. Phys Chem C 2008;112:747–53. An HZ, Du Y, Wang TM, Wang C, Hao WC, Zhang JY. Rare Met 2008;27:243–50. Henle J, Simon P, Frenzel A, Scholz S, Kaskel S. Chem Mater 2007;19:366–73. Zhang KL, Liu CM, Huang FQ, Zheng C, Wang WD. Appl Catal B: Environ 2006;68:125–9.
[6] [7] [8] [9] [10] [11] [12] [13] [14]
157
Ye LQ, Liu JY, Jiang Z, Peng TY, Zan L. Appl Catal B: Environ 2013;142–143:1–7. Deng H, Wang JW, Peng Q, Wang X, Li YD. Chem Eur J 2005;11:6519–24. Huo YN, Zhang J, Miao M, Jin Y. Appl Catal B: Environ 2012;111–112:334–41. Xu J, Meng W, Zhang Y, Li L, Guo CS. Appl Catal B: Environ 2011;107:355–62. Zhou Y, Schattka JH, Antonietti. M. Nano Lett 2004;4:477–81. Zhou Y, Antonietti M. J Am Chem Soc 2003;125:14960–1. Zhu YJ, Wang WW, Qi RJ, Hu XL. Angew Chem Int Ed, 43; 2004; 1410–4. Xia J, Yin S, Li H, Xu H, Xu L, Xu. Y. Dalton Trans 2011;40:5249–58. Zhang DQ, Wen MC, Jiang B, Li GS, Yu JC. J. Hazard Mater 2012;211212:104–11. [15] Zhou X, Xie ZX, Jiang ZY, Kuang Q, Zhang SH, Xu T, et al. Chem Commun 2005;44:5572–4. [16] Li YL, Liu YM, Wang JS, Uchaker E, Zhang QF, Sun SB, et al. J Mater Chem A 2013;1:7949–56. [17] Zhang D, Li J, Wang QG, Wu QS. J Mater Chem A 2013;1:8622–9.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Ionic liquid-assisted hydrothermal synthesis of square BiOBr nanoplates with highly efficient photocatalytic activity Danjun Mao, Xiaomeng Lü, Zhifeng Jiang, Jimin Xie n, Xiufeng Lu, Wei Wei, A.M. Showkot Hossain School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, PR China
art ic l e i nf o
a b s t r a c t
Article history: Received 15 October 2013 Accepted 11 December 2013 Available online 18 December 2013
The square BiOBr nanoplates were successfully synthesized under hydrothermal conditions with the ionic liquids used as solvent, reactant and the directing agent. The prepared BiOBr nanoplates were characterized by XRD, TEM, HRTEM, SAED, EDX, and DRS, which showed that the square BiOBr nanoplates possessed pure tetragonal BiOBr phase with high-ratio exposure of {001} facets. It was found that the ionic liquid played a key role in the formation of square BiOBr nanoplates and the possible growth mechanism was also discussed. According to the results in the photodegradation of Rhodamine B under visible-light irradiation, the square BiOBr nanoplates exhibited excellent photocatalytic activity. & 2013 Elsevier B.V. All rights reserved.
Keywords: BiOBr Square nanoplate Crystal structure Solar energy materials
1. Introduction BiOBr, as one of the important V–VII group compound semiconductors, has attracted considerable attention recently because of its unique and excellent electrical, magnetic, optical, and luminescent properties, in addition to be a new visible light responding photocatalyst [1–4]. Bismuth oxybromide prefers to crystallize in the tetragonal matlockite structure, a layer structure characterized by [Bi2O2] slabs interleaved by double slabs of halogen atoms [5,6]. Inspired by the unique properties and promising photocatalytical applications, many research groups have carried out studies on BiOBr micro/nanostructures. Up to now, a variety of BiOBr micro/ nanostructures, including nanoplates, nanobelts and microspheres, have been synthesized with various approaches [7–9]. However, the fabrication of 2D BiOBr nanostructures with uniform and well defined shapes is still hard to obtain and highly desired. Compared to the conventional organic solvents, the ionic liquids (ILs) can be used as template, solvent and reactor in the synthesis of inorganic materials for its unique properties such as extremely low volatility, high ionic conductivity, good dissolving ability, designable structures, and a large electrochemical window [10–12]. Xia demonstrated the EG-assisted solvothermal synthesis of BiOBr microspheres in the presence of ionic liquid [13]. Zhang et al. reported the hierarchical BiOBr microspheres synthesized by using the ionothermal method at 200 1C [14]. However, to the best of our knowledge, the utilization of ionic liquids, a versatile and
n
Corresponding author. Tel.: þ 86 511 88791708; fax: þ 86 511 88791800. E-mail address: [email protected] (J. Xie).
0167-577X/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.matlet.2013.12.049
environmental medium, in the controlled synthesis of 2D BiOBr nanostructures has not yet been reported. Herein, for the first time, we report a facile and environmentally benign green route to synthesize square BiOBr nanoplates with exposed {001} facets via an ionic liquid-assisted hydrothermal process. In the reaction, ionic liquids were used not only as solvent and reactant, but also as a directing agent in the formation of square BiOBr nanoplates with exposed {001} facets. Moreover, the visible-light-driven photocatalytic activity of the as-obtained BiOBr materials was investigated for the degradation of Rhodamine B (RhB).
2. Experimental section In a typical procedure, 0.97 g of Bi(NO3)3 5H2O was first dissolved in 2 mL of a 2 M nitric acid solution and then it was diluted to 5 mL with deionized water. 0.80 g of [Bmim]Br or 0.43 g of KBr was added slowly into 30 mL of deionized water. Thereafter, a yellow homogeneous solution was obtained when the Bi (NO3)3 5H2O solution was added dropwise into the above solution. After that, 4 mL of NaOH solution (2.0 mol L 1) was slowly added into the mixed solution. The samples denoted as IL-BiOBr and K-BiOBr represent the samples prepared in the presence of [Bmin]Br and KBr, respectively. The solution was stirred for 15 min and transferred to a 50 mL Teflon-lined autoclave, which was placed at 120 1C in an oven for 12 h, and then cooled to room temperature. The product was collected by filtration and washed with deionized water and ethanol for several times, and dried in vacuum at 60 1C overnight.
D. Mao et al. / Materials Letters 118 (2014) 154–157
155
3. Results and discussion
The phase purity and crystal structure of the products were determined by X-ray diffractometer (Bruker AXS Company, Karlsruhe, Germany). Transmission electron microscopy (TEM, JEM-2010, JEOL), high-resolution TEM (HRTEM) and selected area electron diffraction (SAED) were measured at an accelerating voltage of 200 kV. The photocatalytic activities of the samples were evaluated by degradation of Rhodamine B (RhB) in an aqueous solution under visible-light. A 300 W Xe lamp was used as the light source with a 420 nm cutoff filter to provide visible-light irradiation. The photocatalyst (50 mg) was poured in RhB aqueous solution (100 mL, 10 mg L 1) in a Pyrex reactor at room temperature under air. Before illumination, the solution was stirred in the dark for 60 min in order to reach the adsorption–desorption equilibrium of RhB on the photocatalysts. The concentrations of RhB were monitored with a UV–vis spectrophotometer in terms of the absorbance at 553 nm during the photodegradation process.
The morphology and structure of the samples were revealed by TEM, HRTEM images and SAED patterns. As shown in Fig. 1(a,b), the IL-BiOBr nanoplates are square and nanoplate geometric shapes. It was also clearly observed that the IL-BiOBr nanoplates were 120–270 nm in width and 20–35 nm in thickness. The SAED pattern of an individual IL-BiOBr nanoplate (Fig. 1c) shows the clear electron diffraction (ED) spots with well alignment, indicating the single-crystal nature of the nanoplate. The angle labeled in the SAED pattern is 451, which is in good agreement with the theoretical value of the angle between the (110) and (200) planes. The set of diffraction spots can be indexed as the [001] zone axis of tetragonal BiOBr. HRTEM image of IL-BiOBr (Fig. 1d) revealed the highly crystalline nature of the nanoplates. The clear lattice fringes with an interplanar lattice spacing of 0.269 nm correspond to the
110 200 45 110
0.269nm Fig. 1. TEM (a,b), SAED patterns (c) and HRTEM (d) images of the IL-BiOBr square nanoplates. TEM (e,f) images of the K-BiOBr nanosheets.
400
intensity (a.u.)
(105)
(204) (220) (006) (214) (106) (310) (116)
(004) (200) (113) (104) (211) (114) (212)
IL-BiOBr
(112)
intensity (a.u.)
(101)
(003)
(002)
(110)
(001)
(102)
500
Bi Br
300
200
K-BiOBr 100
O Br
standard spectrum
Bi
0 10
20
30
40
50
2 (degree)
60
70
80
1
2
3
4
5
6
7
Energy(keV)
Fig. 2. (a) XRD patterns of the BiOBr samples and (b) EDX spectrum of the IL-BiOBr square nanoplates.
8
9
10
11
156
D. Mao et al. / Materials Letters 118 (2014) 154–157
(003) atomic planes. As shown in Fig. 1(e,f), the TEM images showed that the K-BiOBr sample is composed of irregular nanosheets with widths of 0.5–2.0 μm. The phase and composition of as-prepared samples were examined using powder XRD measurements. As shown in Fig. 2a, all the peaks can be indexed to the tetragonal phase BiOBr with lattice constants of a¼b¼3.926 Å and c¼8.103 Å (JCPDS Card no. 09-0393). No other phases were detected. The peak intensities for the K-BiOBr sample highly match the standard spectrum, which is shown in the bottom of Fig. 2a. As for the IL-BiOBr sample, a great increase on the relative intensity of (001) series peaks can be found, which is labeled with “▼” in the figure. Typically, the intensity ratio of the (001) to (102) peak is 0.98, obviously larger than the standard value of 0.4, indicating that the crystal has special anisotropic growth along the (001) plane, in good agreement with the HRTEM and SAED results. Based on the above results and the symmetries of tetragonal BiOBr, the preponderant growth direction of square BiOBr nanoplates was the [001] orientation. In addition, the energy-dispersive X-ray (EDX) spectrum of the IL-BiOBr sample (Fig. 2b) also reveals that the atomic ratio of Bi/Br in the sample is approximately equal to 1:1, which is consistent with the XRD results. The ionic liquids played a vital role in the formation of the square BiOBr nanoplates with exposed {001} facets. It is believed
2.0
0.8
Absorbance (a.u.)
1.5
1.0
0.6
0.5
0.0
0.4
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
that the surface energy of the facets can be reduced by compensating the surface charge with a passivating reagent such as an ionic liquid [15]. Due to the strong electrostatic interactions between the ions of the ionic liquid and the O-terminated (001) facets of BiOBr [16], the surface energies of the (001) facets may decrease greatly in comparison to those of other crystal faces, resulting in a relatively slow growth rate for the (001) facets. Thus the (001) facets may appear as exposed facet, as in the square structure. The UV–vis diffuse-reflectance spectrum reveals that the absorption edge of the IL-BiOBr square nanoplates extended to the visible-light region, which indicates the possibility of high photocatalytic activity of these materials under visible-light irradiation (Fig. 3). The absorption onset of the square nanoplate is at ca. 445 nm, corresponding to a band-gap energy of about 2.62 eV, which is consistent with previous studies (2.75 eV) [6]. We evaluated photocatalytic activities of the as-prepared IL-BiOBr and K-BiOBr samples by degradation of RhB and compared them with P25. The results in Fig. 4(a) indicate that IL-BiOBr exhibits excellent performance in terms of both adsorption and degradation of RhB. The intensity of RhB at its main absorbance peak diminishes sharply to 43.5% of its original value in the dark, and almost totally disappears in 90 min under visible-light. However, the K-BiOBr sample shows a poor adsorption amount of 23.3% and also a poor degradation amount of 65.7% after 90 min visible-light irradiation. Such a significant improvement in efficiency of IL-BiOBr samples was mainly attributed to its higher adsorption capacity by high-ratio exposure of {001} facets and higher separation efficiency of photogenerated carriers due to the self-built electric field [17]. Thus, the square BiOBr nanoplates with exposed {001} facets show highly efficient photocatalytic activity to RhB under visible-light.
4.0
0.2
4. Conclusion
0.0 200
300
400
500
600
700
800
Wavelength (nm) Fig. 3. UV–vis diffusion reflectance spectra of the IL-BiOBr square nanoplates. Inset: curves of (αhν)1/2 vs. photon energy.
In summary, square BiOBr nanoplates with exposed {001} facets have been successfully synthesized via an ionic liquidassisted hydrothermal approach. The possible formation mechanism is discussed. The resulting BiOBr square nanoplates exhibited excellent visible-light-driven photocatalytic activity. This work not only provides a new route to fabricate 2D BiOBr nanostructures, but also facilitate the reasonable design and performance enhancement of photocatalysts.
1.0
RhB photodegradation (C/Co)
Absorbance (a.u.)
0.8
0 min 15 min 30 min 45 min 60 min 75 min 90 min
0.6
0.4
0.2
0.0 200
300
400
500
600
Wavelength / nm
700
blank RhB
1.0
IL-BiOBr
800
P25
0.8 0.6
K-BiOBr
0.4 0.2 0.0 -60
light on
0
IL-BiOBr
15
30
45
60
75
90
Irradiation time / min
Fig. 4. (a) UV–vis absorption spectral and (b) the photodegradation efficiency of the photodegradation of RhB under visible-light irradiation (λ Z420 nm).
D. Mao et al. / Materials Letters 118 (2014) 154–157
Acknowledgments This work was supported by the National Natural Science Foundation of China (Grant No. 21003065) and Natural Science Foundation of Jiangsu Province (BK2010044). References [1] [2] [3] [4] [5]
Deng ZT, Chen D, Peng B, Tang FQ. Cryst Growth Des 2008;8:29953003. Zhang X, Ai ZH, Jia FL, Zhang LZJ. Phys Chem C 2008;112:747–53. An HZ, Du Y, Wang TM, Wang C, Hao WC, Zhang JY. Rare Met 2008;27:243–50. Henle J, Simon P, Frenzel A, Scholz S, Kaskel S. Chem Mater 2007;19:366–73. Zhang KL, Liu CM, Huang FQ, Zheng C, Wang WD. Appl Catal B: Environ 2006;68:125–9.
[6] [7] [8] [9] [10] [11] [12] [13] [14]
157
Ye LQ, Liu JY, Jiang Z, Peng TY, Zan L. Appl Catal B: Environ 2013;142–143:1–7. Deng H, Wang JW, Peng Q, Wang X, Li YD. Chem Eur J 2005;11:6519–24. Huo YN, Zhang J, Miao M, Jin Y. Appl Catal B: Environ 2012;111–112:334–41. Xu J, Meng W, Zhang Y, Li L, Guo CS. Appl Catal B: Environ 2011;107:355–62. Zhou Y, Schattka JH, Antonietti. M. Nano Lett 2004;4:477–81. Zhou Y, Antonietti M. J Am Chem Soc 2003;125:14960–1. Zhu YJ, Wang WW, Qi RJ, Hu XL. Angew Chem Int Ed, 43; 2004; 1410–4. Xia J, Yin S, Li H, Xu H, Xu L, Xu. Y. Dalton Trans 2011;40:5249–58. Zhang DQ, Wen MC, Jiang B, Li GS, Yu JC. J. Hazard Mater 2012;211212:104–11. [15] Zhou X, Xie ZX, Jiang ZY, Kuang Q, Zhang SH, Xu T, et al. Chem Commun 2005;44:5572–4. [16] Li YL, Liu YM, Wang JS, Uchaker E, Zhang QF, Sun SB, et al. J Mater Chem A 2013;1:7949–56. [17] Zhang D, Li J, Wang QG, Wu QS. J Mater Chem A 2013;1:8622–9.