- Email: [email protected]
Facile fabrication of CeVO4 hierarchical hollow microspheres with enhanced photocatalytic activity
Materials Letters 253 (2019) 259–262
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Facile fabrication of CeVO4 hierarchical hollow microspheres with enhanced photocatalytic activity Miao Wang, Xiaoman Hu, Zhangyu Zhan, Tongming Sun ⇑, Yanfeng Tang ⇑ School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, PR China
a r t i c l e
i n f o
a b s t r a c t Hierarchical hollow CeVO4 microspheres with average size about 5 lm and the thickness of shell walls about 500 nm were fabricated via a simple hydrothermal method with L-Aspartic acid (L-Asp) as the structure-directing agent. SEM results indicate that hierarchical hollow CeVO4 microspheres are assembled by numerous nanoflakes with thickness of 30–40 nm. The dimensions and hollowness of the hollow microspheres can be tailored via the appropriate controlling of reaction time and the amount of L-Asp. N2 adsorption-desorption measurements revealed the BET surface area of the nanoflakes-assembled CeVO4 hollow microspheres was 98.24 m2/g. The photocatalytic properties of CeVO4 were investigated by the degradation of methylene orange (MO) under UV light irradiation. This excellent performance can be ascribed to the synergistic effect of hollow nature and hierarchical structures, which endowing CeVO4 great potential for purifying organic pollutants. Ó 2019 Elsevier B.V. All rights reserved.
Article history: Received 30 April 2019 Received in revised form 22 June 2019 Accepted 25 June 2019 Available online 26 June 2019 Keywords: Hollow microspheres Nanocrystalline materials CeVO4 Microstructure Crystal growth
1. Introduction Because of the distinguished properties (e.g., large surface area, low density, high loading capacity and efficient light-harvesting ability), micro/nanomaterials with hollow structure have generated considerable interest for their wide variety of applications in catalysis, drug delivery and waste removal [1–4]. Therefore, numerous research efforts have been exerted for the controlled creation of hollow structures in order to fully exploit the potentials of different material systems. Among them, amino acid assisted method provide a new alternative, which can facilitate the nucleation and crystal growth process of nanostructures as an efficient structure-directing ligand. By virtue of its advantages of nontoxicity and biocompatibility, amino acid assisted routes have received particular attention. Up to now, a variety of novel hollow micro/nanostructures have been fabricated by L-Asp assisted route, such as nanoparticle-assembled hollow yolk–shell ZnWO4 microspheres [5], CaWO4 hollow spheres and nanowireassembled hollow YVO4 microspheres [6,7]. As an important semiconductor, CeVO4 have been actively pursued in catalysis and gas sensors fields [8,9]. Particularly, CeVO4 micro/nanocrystals possesses the excellent photocatalytic properties due to the excellent crystallinity, suitable electronic band
⇑ Corresponding authors. E-mail (Y. Tang).
addresses:
[email protected]
(M.
https://doi.org/10.1016/j.matlet.2019.06.081 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Wang),
[email protected]
structure and wide range of light absorption [10,11]. To date, various micro/nanosized CeVO4 structures have been prepared, including micro/nanorods, nanoplates, nanobelts and microspheres [8–11]. Regardless several shapes of CeVO4 have been obtained, reports on the preparation of hierarchical hollow structures are still limited yet. From the photocatalytical points of view, hierarchical hollow structures built by nanoscaled units possess large surface area and more active sites, which are feasible to the better contact of the reactants with the surface of CeVO4 and transport of organic pollutants. Herein, using L-Asp as structure and surface directing agent, nanoflakes-assembled hollow microspheres with tunable hollowness and porosity were prepared. L-Asp and reaction time play key roles in the formation of different morphological CeVO4. Furthermore, the photocatalytic activities of the hollow CeVO4 microspheres were investigated by the decomposition of MO under UV irradiation. This excellent photocatalytic property can be attributed to the hollow nature, the synergistic effect of the nanoscaled building units and secondary microarchitecture, indicating the design of a hierarchical hollow architecture is an effective method to enhance the photocatalytic performance of semiconductors.
2. Experimental section All the chemicals including L-Asp, NH4VO3 and Ce(NO3)36H2O were of analytical grade. A typical procedure for the preparation of hierarchical CeVO4 hollow microspheres is given below.
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M. Wang et al. / Materials Letters 253 (2019) 259–262
1.0 mmol Ce(NO3)36H2O and 1.0 mmol L-Asp were dissolved in 25 mL distilled water and the mixture was stirred for 20 min, then 1.0 mmol NH4VO3 was put into the solution. Stirring for 20 min, the obtained suspension was transferred into a 30 mL Teflonlined autoclave. After being sealed and heated at 150 °C for 12 h, the autoclave was gradually cooled to room temperature. The products were precipitated by centrifugation, washed with distilled water and ethanol and finally dried at 70 °C for 3 h. The crystalline structures and the morphology of the series samples were analyzed by X-ray diffraction (XRD, Bruker Advance D-8) and scanning electron microscope (SEM, Hitachi S-4800). The N2 adsorption-desorption isotherms were characterized on a Micromeritics ASAP 2020C apparatus. The surface area was examined by the BET method. The diffuse-reflectance spectra (DRS) and UV–vis absorption spectrum were recorded with a Shimadzu UV-3600 spectrometer. The photocatalytic activity of the as-obtained CeVO4 was evaluated by degradation of aqueous MO in an XPA-7 photochemical reactor equipped with a 300 W high-pressure mercury lamp (k = 365 nm). The suspension was vigorously stirred during the whole process. Typically, 16 mg of CeVO4 powders were put into a series of quartz cuvettes containing 20 mL of MO aqueous solution (20 mg/L), respectively, then it was stirred for 30 min in the dark to achieve adsorption–desorption equilibrium before irradiation. During irradiation, the quartz cuvette was orderly taken from the reactor at a given time. 3.5 mL of the solution was taken out and centrifuged to remove the catalysts. 3. Results and discussion The crystal phase and purity of the products were characterized by XRD, as shown in Fig. 1a, the diffraction peaks of the products obtained from 3 h, 6 h and 12 h are all be indexed to the tetragonal phase of CeVO4 (JCPDS card No. 12-0757). Compared with 3 h, the
6h 1h 30
40
50
2theta(degree)
60
70
3 Quantity Adsorbed(cm /g STP)
332 204 431 224
420
103 321 312 400 213
220 202 301
112
200
12h
20
in Fig. 2a), the nanoflake appears flat and smooth and the thickness is about 30–40 nm. The initial flower-like structures are aggregated together into microspheres and the dimensions are increased to 2–3 lm within 3 h (Fig. 2b). Further prolonging time to 6 h and 9 h, a large number of nanoflakes-assembled hollow microspheres are obtained (Fig. 2c-d). The diameter of the sphere is about 4–5 lm, which is larger than that of 3 h. From the broken hollow spheres, it is observed that the thickness of the shell wall is
70
211
101
Relative intensity(a.u.)
a
diffraction peaks of the samples obtained from 12 h are much sharper, revealing that the crystallinity improved or the particle size increased after prolonging the reaction time. The BET specific surface area of the typical CeVO4 hollow microspheres was investigated by N2 adsorption–desorption measurements (Fig. 1b). The BET surface area of the CeVO4 hollow microspheres is 98.24 m2/g. The isotherms for the as-prepared CeVO4 hollow microspheres are characteristic of a type IV isotherm with a type H3 hysteresis loop [9], indicating the presence of mesopores in the sample. The sizes and morphologies of the as-prepared products in typical process were characterized by SEM. Fig. 1c is lowmagnification SEM image, there are a great deal of aggregated uniform broken hollow spheres with diameter of 4–5 lm. The external surfaces of the shell walls are extensively roughened, whereas the inner surfaces are smooth. High-magnification images (Fig. 1d) clearly show that the shell walls are approximately 500– 600 nm thick. The thickness of the shell wall is about one eighth of the sphere diameter. The spheres are constructed by a large amount of nanoflakes with a small thickness of 30–40 nm. To better understand the growth details of hierarchical hollow microspheres of CeVO4, time-dependent experiments were carried out. The representative SEM images of the samples are shown in Fig. 2a–d. As shown in Fig. 2a, many loosely-arranged nanostructures are formed in a period of 1 h, which are similar in appearance to flowers with an diameter of 1–1.5 lm, which are crossed each other and assembled by nanoflakes. From the enlarged image (inset
60
b
50 40 30 20 10 0 0.0
0.2
0.4
0.6
0.8
1.0
Relative Pressure(p/p0)
Fig. 1. (a) XRD patterns of the products, (b) N2 adsorption–desorption isotherm and (c-d) SEM image of CeVO4 obtained from typical process.
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M. Wang et al. / Materials Letters 253 (2019) 259–262
Fig. 2. SEM images of the products obtained from different time and amount of L-Asp. (a) 1 h; (b) 3 h; (c) 6 h; (d) 9 h with 1 mmol L-Asp; 2 mmol (e) and 0 mmol (f) L-Asp within 12 h.
decreased from 6 h to 12 h. Obviously, there is a time-dependent self-assembly induced morphological evolution process from nanoflakes-assembled microflowers to hollow microspheres, revealing Ostwald ripening is the dominant mechanism. On the other hand, the amount of L-Asp also plays important roles in determining the growth process and final morphologies of the CeVO4. Similar procedures were performed under the same reaction condition except using different amount of L-Asp. When 2.0 mmol L-Asp was used, nanocubes-assembled hollow microspheres with a mean size of 5 lm are prepared within 12 h (Fig. 2e). While a number of irregular nanorods are formed in the absence of L-Asp, as shown in Fig. 2f. Herein, our choice of
properties of the different morphological CeVO4 were investigated by the decomposition of MO under UV light irradiation. MO concentration ratio (C/C0) as a function of irradiation time for nanorods, nanoflakes-assembled and nanocubes-assembled hollow microspheres of CeVO4 under the same condition are plotted as Fig. 3b. The degradation of MO is very slow without any photocatalyst. Compared with other samples, nanoflakes-assembled hollow microspheres exhibit the best efficiency, implying this kind of architectures have excellent photocatalytic activity. This excellent performance can be ascribed to the synergistic effect of hollow nature and hierarchical structures.
L-Asp
4. Conclusions
is mainly based on its appropriately chelating and capping effects, which influenced the growth rate of different facets distinguishingly. The DRS of the CeVO4 obtained in typical process was shown in Fig. 3a. The peak located at 258 nm is assigned to the absorption of VO34 group [12,13]. Moreover, there is a broad absorption peak ranging from 300 to 550 nm, implying the possibility of UV light photocatalytic activity. The energy band gaps of hollow microspheres of CeVO4 are calculated as 3.3 eV according to the (ahm)2 versus hm curve (inset in Fig. 3a), which are consistent with the results in reported the literature [14]. The photocatalytic
Hierarchical hollow CeVO4 microspheres assembled by nanoflakes were prepared by a facile L-Asp assisted hydrothermal method. Reaction time and the amount of L-Asp are two key factors in the formation of such unique architectures. Due to the large surface area and unique hollow hierarchical structure, hollow CeVO4 microspheres exhibit good photocatalytic properties by the degradation of MO solution under UV light irradiation, indicating the hierarchical hollow microspheres of CeVO4 can be used as promising photocatalysts for the degradation of organic pollutants.
1.0
b
0.8
h
Absorbance(a.u.)
a
3
4
5
6
h (eV)
C/C0
0.6 0.4
without catalyst nanocubes-assembled microspheres nanoflakes-assembled microspheres nanorods
0.2 0.0 200
300
400
Wavelength(nm)
500
600
0
10
20
30
40
50
T/min
Fig. 3. (a) DRS of the as-obtained CeVO4 and the plots of (ahm)2 versus hm, the photodegradation efficiencies of MO as a function of irradiation time (b).
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M. Wang et al. / Materials Letters 253 (2019) 259–262
Declaration of Competing Interest The authors have declared that no competing interests exist. Acknowledgments This work was supported by National Natural Science Foundation of China (No. 21776140), High-level Talents in Six Industries of Jiangsu Province (XCL-062), Ph.D Startup Project of Nantong University (03082100) and Training Programs of Innovation for Undergraduates. References [1] G. Prieto, H. Tueysuez, N. Duyckaerts, et al., Chem. Rev. 116 (2016) 14056– 14119.
[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
L. Zhou, Z. Zhuang, H. Zhao, et al., Adv. Mater. 29 (2017) 1602914. X.J. Lin, T.Q. Sun, L.P. Yang, et al., Chem. Commun. 55 (2019) 1076–1079. D.S. Bin, Z.X. Chi, Y. Li, et al., J. Am. Chem. Soc. 139 (2017) 13492–13498. M. Wang, Y.F. Tang, T.M. Sun, et al., CrystEngComm 16 (2014) 11035–11041. M. Wang, Y.J. Shi, Y.F. Tang, et al., Mater. Lett. 132 (2014) 236–239. M. Wang, Y.J. Shi, Y.F. Tang, et al., Mater. Lett. 109 (2013) 12–15. F. Luo, C.J. Jia, R. Liu, et al., Mater. Res. Bull. 48 (2013) 1122–1127. L. Wang, W.W. Meng, Z.X. He, et al., Sens. Actuators, B. 272 (2018) 219–228. L.B. Yao, E.Y. Guo, K. Sun, et al., Mater. Lett. 231 (2018) 11–15. J. Ren, Y.Z. Wu, H. Zou, et al., Mater. Lett. 183 (2016) 219–222. L. Li, H.R. Wang, X. Wang, Solid. State. Commun. 269 (2018) 11–15. H. Wang, Y.Q. Meng, H. Yan, et al., Inorg. Chem. Commun. 7 (2004) 553–555. X.J. Yang, W.L. Zuo, F. Li, et al., ChemistryOpen 4 (2015) 288–294.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Facile fabrication of CeVO4 hierarchical hollow microspheres with enhanced photocatalytic activity Miao Wang, Xiaoman Hu, Zhangyu Zhan, Tongming Sun ⇑, Yanfeng Tang ⇑ School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, PR China
a r t i c l e
i n f o
a b s t r a c t Hierarchical hollow CeVO4 microspheres with average size about 5 lm and the thickness of shell walls about 500 nm were fabricated via a simple hydrothermal method with L-Aspartic acid (L-Asp) as the structure-directing agent. SEM results indicate that hierarchical hollow CeVO4 microspheres are assembled by numerous nanoflakes with thickness of 30–40 nm. The dimensions and hollowness of the hollow microspheres can be tailored via the appropriate controlling of reaction time and the amount of L-Asp. N2 adsorption-desorption measurements revealed the BET surface area of the nanoflakes-assembled CeVO4 hollow microspheres was 98.24 m2/g. The photocatalytic properties of CeVO4 were investigated by the degradation of methylene orange (MO) under UV light irradiation. This excellent performance can be ascribed to the synergistic effect of hollow nature and hierarchical structures, which endowing CeVO4 great potential for purifying organic pollutants. Ó 2019 Elsevier B.V. All rights reserved.
Article history: Received 30 April 2019 Received in revised form 22 June 2019 Accepted 25 June 2019 Available online 26 June 2019 Keywords: Hollow microspheres Nanocrystalline materials CeVO4 Microstructure Crystal growth
1. Introduction Because of the distinguished properties (e.g., large surface area, low density, high loading capacity and efficient light-harvesting ability), micro/nanomaterials with hollow structure have generated considerable interest for their wide variety of applications in catalysis, drug delivery and waste removal [1–4]. Therefore, numerous research efforts have been exerted for the controlled creation of hollow structures in order to fully exploit the potentials of different material systems. Among them, amino acid assisted method provide a new alternative, which can facilitate the nucleation and crystal growth process of nanostructures as an efficient structure-directing ligand. By virtue of its advantages of nontoxicity and biocompatibility, amino acid assisted routes have received particular attention. Up to now, a variety of novel hollow micro/nanostructures have been fabricated by L-Asp assisted route, such as nanoparticle-assembled hollow yolk–shell ZnWO4 microspheres [5], CaWO4 hollow spheres and nanowireassembled hollow YVO4 microspheres [6,7]. As an important semiconductor, CeVO4 have been actively pursued in catalysis and gas sensors fields [8,9]. Particularly, CeVO4 micro/nanocrystals possesses the excellent photocatalytic properties due to the excellent crystallinity, suitable electronic band
⇑ Corresponding authors. E-mail (Y. Tang).
addresses:
[email protected]
(M.
https://doi.org/10.1016/j.matlet.2019.06.081 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
Wang),
[email protected]
structure and wide range of light absorption [10,11]. To date, various micro/nanosized CeVO4 structures have been prepared, including micro/nanorods, nanoplates, nanobelts and microspheres [8–11]. Regardless several shapes of CeVO4 have been obtained, reports on the preparation of hierarchical hollow structures are still limited yet. From the photocatalytical points of view, hierarchical hollow structures built by nanoscaled units possess large surface area and more active sites, which are feasible to the better contact of the reactants with the surface of CeVO4 and transport of organic pollutants. Herein, using L-Asp as structure and surface directing agent, nanoflakes-assembled hollow microspheres with tunable hollowness and porosity were prepared. L-Asp and reaction time play key roles in the formation of different morphological CeVO4. Furthermore, the photocatalytic activities of the hollow CeVO4 microspheres were investigated by the decomposition of MO under UV irradiation. This excellent photocatalytic property can be attributed to the hollow nature, the synergistic effect of the nanoscaled building units and secondary microarchitecture, indicating the design of a hierarchical hollow architecture is an effective method to enhance the photocatalytic performance of semiconductors.
2. Experimental section All the chemicals including L-Asp, NH4VO3 and Ce(NO3)36H2O were of analytical grade. A typical procedure for the preparation of hierarchical CeVO4 hollow microspheres is given below.
260
M. Wang et al. / Materials Letters 253 (2019) 259–262
1.0 mmol Ce(NO3)36H2O and 1.0 mmol L-Asp were dissolved in 25 mL distilled water and the mixture was stirred for 20 min, then 1.0 mmol NH4VO3 was put into the solution. Stirring for 20 min, the obtained suspension was transferred into a 30 mL Teflonlined autoclave. After being sealed and heated at 150 °C for 12 h, the autoclave was gradually cooled to room temperature. The products were precipitated by centrifugation, washed with distilled water and ethanol and finally dried at 70 °C for 3 h. The crystalline structures and the morphology of the series samples were analyzed by X-ray diffraction (XRD, Bruker Advance D-8) and scanning electron microscope (SEM, Hitachi S-4800). The N2 adsorption-desorption isotherms were characterized on a Micromeritics ASAP 2020C apparatus. The surface area was examined by the BET method. The diffuse-reflectance spectra (DRS) and UV–vis absorption spectrum were recorded with a Shimadzu UV-3600 spectrometer. The photocatalytic activity of the as-obtained CeVO4 was evaluated by degradation of aqueous MO in an XPA-7 photochemical reactor equipped with a 300 W high-pressure mercury lamp (k = 365 nm). The suspension was vigorously stirred during the whole process. Typically, 16 mg of CeVO4 powders were put into a series of quartz cuvettes containing 20 mL of MO aqueous solution (20 mg/L), respectively, then it was stirred for 30 min in the dark to achieve adsorption–desorption equilibrium before irradiation. During irradiation, the quartz cuvette was orderly taken from the reactor at a given time. 3.5 mL of the solution was taken out and centrifuged to remove the catalysts. 3. Results and discussion The crystal phase and purity of the products were characterized by XRD, as shown in Fig. 1a, the diffraction peaks of the products obtained from 3 h, 6 h and 12 h are all be indexed to the tetragonal phase of CeVO4 (JCPDS card No. 12-0757). Compared with 3 h, the
6h 1h 30
40
50
2theta(degree)
60
70
3 Quantity Adsorbed(cm /g STP)
332 204 431 224
420
103 321 312 400 213
220 202 301
112
200
12h
20
in Fig. 2a), the nanoflake appears flat and smooth and the thickness is about 30–40 nm. The initial flower-like structures are aggregated together into microspheres and the dimensions are increased to 2–3 lm within 3 h (Fig. 2b). Further prolonging time to 6 h and 9 h, a large number of nanoflakes-assembled hollow microspheres are obtained (Fig. 2c-d). The diameter of the sphere is about 4–5 lm, which is larger than that of 3 h. From the broken hollow spheres, it is observed that the thickness of the shell wall is
70
211
101
Relative intensity(a.u.)
a
diffraction peaks of the samples obtained from 12 h are much sharper, revealing that the crystallinity improved or the particle size increased after prolonging the reaction time. The BET specific surface area of the typical CeVO4 hollow microspheres was investigated by N2 adsorption–desorption measurements (Fig. 1b). The BET surface area of the CeVO4 hollow microspheres is 98.24 m2/g. The isotherms for the as-prepared CeVO4 hollow microspheres are characteristic of a type IV isotherm with a type H3 hysteresis loop [9], indicating the presence of mesopores in the sample. The sizes and morphologies of the as-prepared products in typical process were characterized by SEM. Fig. 1c is lowmagnification SEM image, there are a great deal of aggregated uniform broken hollow spheres with diameter of 4–5 lm. The external surfaces of the shell walls are extensively roughened, whereas the inner surfaces are smooth. High-magnification images (Fig. 1d) clearly show that the shell walls are approximately 500– 600 nm thick. The thickness of the shell wall is about one eighth of the sphere diameter. The spheres are constructed by a large amount of nanoflakes with a small thickness of 30–40 nm. To better understand the growth details of hierarchical hollow microspheres of CeVO4, time-dependent experiments were carried out. The representative SEM images of the samples are shown in Fig. 2a–d. As shown in Fig. 2a, many loosely-arranged nanostructures are formed in a period of 1 h, which are similar in appearance to flowers with an diameter of 1–1.5 lm, which are crossed each other and assembled by nanoflakes. From the enlarged image (inset
60
b
50 40 30 20 10 0 0.0
0.2
0.4
0.6
0.8
1.0
Relative Pressure(p/p0)
Fig. 1. (a) XRD patterns of the products, (b) N2 adsorption–desorption isotherm and (c-d) SEM image of CeVO4 obtained from typical process.
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M. Wang et al. / Materials Letters 253 (2019) 259–262
Fig. 2. SEM images of the products obtained from different time and amount of L-Asp. (a) 1 h; (b) 3 h; (c) 6 h; (d) 9 h with 1 mmol L-Asp; 2 mmol (e) and 0 mmol (f) L-Asp within 12 h.
decreased from 6 h to 12 h. Obviously, there is a time-dependent self-assembly induced morphological evolution process from nanoflakes-assembled microflowers to hollow microspheres, revealing Ostwald ripening is the dominant mechanism. On the other hand, the amount of L-Asp also plays important roles in determining the growth process and final morphologies of the CeVO4. Similar procedures were performed under the same reaction condition except using different amount of L-Asp. When 2.0 mmol L-Asp was used, nanocubes-assembled hollow microspheres with a mean size of 5 lm are prepared within 12 h (Fig. 2e). While a number of irregular nanorods are formed in the absence of L-Asp, as shown in Fig. 2f. Herein, our choice of
properties of the different morphological CeVO4 were investigated by the decomposition of MO under UV light irradiation. MO concentration ratio (C/C0) as a function of irradiation time for nanorods, nanoflakes-assembled and nanocubes-assembled hollow microspheres of CeVO4 under the same condition are plotted as Fig. 3b. The degradation of MO is very slow without any photocatalyst. Compared with other samples, nanoflakes-assembled hollow microspheres exhibit the best efficiency, implying this kind of architectures have excellent photocatalytic activity. This excellent performance can be ascribed to the synergistic effect of hollow nature and hierarchical structures.
L-Asp
4. Conclusions
is mainly based on its appropriately chelating and capping effects, which influenced the growth rate of different facets distinguishingly. The DRS of the CeVO4 obtained in typical process was shown in Fig. 3a. The peak located at 258 nm is assigned to the absorption of VO34 group [12,13]. Moreover, there is a broad absorption peak ranging from 300 to 550 nm, implying the possibility of UV light photocatalytic activity. The energy band gaps of hollow microspheres of CeVO4 are calculated as 3.3 eV according to the (ahm)2 versus hm curve (inset in Fig. 3a), which are consistent with the results in reported the literature [14]. The photocatalytic
Hierarchical hollow CeVO4 microspheres assembled by nanoflakes were prepared by a facile L-Asp assisted hydrothermal method. Reaction time and the amount of L-Asp are two key factors in the formation of such unique architectures. Due to the large surface area and unique hollow hierarchical structure, hollow CeVO4 microspheres exhibit good photocatalytic properties by the degradation of MO solution under UV light irradiation, indicating the hierarchical hollow microspheres of CeVO4 can be used as promising photocatalysts for the degradation of organic pollutants.
1.0
b
0.8
h
Absorbance(a.u.)
a
3
4
5
6
h (eV)
C/C0
0.6 0.4
without catalyst nanocubes-assembled microspheres nanoflakes-assembled microspheres nanorods
0.2 0.0 200
300
400
Wavelength(nm)
500
600
0
10
20
30
40
50
T/min
Fig. 3. (a) DRS of the as-obtained CeVO4 and the plots of (ahm)2 versus hm, the photodegradation efficiencies of MO as a function of irradiation time (b).
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M. Wang et al. / Materials Letters 253 (2019) 259–262
Declaration of Competing Interest The authors have declared that no competing interests exist. Acknowledgments This work was supported by National Natural Science Foundation of China (No. 21776140), High-level Talents in Six Industries of Jiangsu Province (XCL-062), Ph.D Startup Project of Nantong University (03082100) and Training Programs of Innovation for Undergraduates. References [1] G. Prieto, H. Tueysuez, N. Duyckaerts, et al., Chem. Rev. 116 (2016) 14056– 14119.
[2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
L. Zhou, Z. Zhuang, H. Zhao, et al., Adv. Mater. 29 (2017) 1602914. X.J. Lin, T.Q. Sun, L.P. Yang, et al., Chem. Commun. 55 (2019) 1076–1079. D.S. Bin, Z.X. Chi, Y. Li, et al., J. Am. Chem. Soc. 139 (2017) 13492–13498. M. Wang, Y.F. Tang, T.M. Sun, et al., CrystEngComm 16 (2014) 11035–11041. M. Wang, Y.J. Shi, Y.F. Tang, et al., Mater. Lett. 132 (2014) 236–239. M. Wang, Y.J. Shi, Y.F. Tang, et al., Mater. Lett. 109 (2013) 12–15. F. Luo, C.J. Jia, R. Liu, et al., Mater. Res. Bull. 48 (2013) 1122–1127. L. Wang, W.W. Meng, Z.X. He, et al., Sens. Actuators, B. 272 (2018) 219–228. L.B. Yao, E.Y. Guo, K. Sun, et al., Mater. Lett. 231 (2018) 11–15. J. Ren, Y.Z. Wu, H. Zou, et al., Mater. Lett. 183 (2016) 219–222. L. Li, H.R. Wang, X. Wang, Solid. State. Commun. 269 (2018) 11–15. H. Wang, Y.Q. Meng, H. Yan, et al., Inorg. Chem. Commun. 7 (2004) 553–555. X.J. Yang, W.L. Zuo, F. Li, et al., ChemistryOpen 4 (2015) 288–294.