Reactable Polyelectrolyte-Assisted Synthesis of BiOCl with Enhanced

Dec 22, 2016 - Dimple P. Dutta , Anand Ballal , Suresh Chopade , Asheesh Kumar. Journal of Photochemistry and Photobiology A: Chemistry 2017 346, 105-...
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Reactable Polyelectrolyte-Assisted Synthesis of BiOCl with Enhanced Photocatalytic Activity Shuo Zhao, Yiwei Zhang,* Yuming Zhou,* Chao Zhang, Xiaoli Sheng, Jiasheng Fang, and Mingyu Zhang School of Chemistry and Chemical Engineering, Southeast University, Jiangsu Optoelectronic Functional Materials and Engineering Laboratory, Nanjing 211189, P. R. China

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ABSTRACT: The reactable polyelectrolyte, poly(allylamine hydrochloride), was used for the first time to fabricate BiOCl materials via an assisted solvothermal method. The influence of polyelectrolyte concentrations on the formation of BiOCl was systematically investigated. The samples were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N2 gas sorption, infrared spectroscopy (FT-IR), as well as ultraviolet−visible diffuse reflectance spectroscopy (DRS). The results showed that the polyelectrolyte, which acted as reactant, template, or structure-directing agent, had a great effect on the structure of as-fabricated BiOCl materials during the reactive process. The possible formation mechanism of the BiOCl materials has been studied. Moreover, the photocatalytic activity of the as-fabricated BiOCl was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. Furthermore, the relationship between the structure of the BiOCl materials and the photocatalyic activity was studied in detail. The holes rather than •OH were the predominant active species in the photocatalytic process. Also, it can be supposed that the improved light harvesting, high surface area, O-vacancies, enhanced adsorption capability of dye, faster interfacial charge separation, and the special structure of BiOCl had contributed to the good photocatalytic activity and high photostability of BiOCl microspheres. This route preparing the BiOCl materials with special structure can be expected to be applicable to the preparation of other materials with novel morphologies and advanced properties in all kinds of fields, including photocatalysis and electrochemistry. KEYWORDS: BiOCl, Polyelectrolyte, Photocatalytic, Visible light

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catalytic properties.13−16 BiOCl possesses a layered structure made of [Bi2O2]2+ layers caught in the middle of two Cl ions ([Cl−Bi−O−Bi−Cl]).15,17,18 Particularly, the layered structure is beneficial for reducing the recombination rate of the photogenerated electron−hole pairs due to the presence of internal static electric fields, which is very important for photocatalysis.19 Because of the interaction between the morphology of the photocatalyst (such as the size, the shape, and the exposed facets) and the photocatalytic activity,20−22 it is promising and indispensable to synthesize the novel microsized BiOCl materials which possess easy recycling properties and high photocatalytic activity.23 Wang’s group15 prepared porous BiOCl microflowers with ultrathin nanosheets using KCl as Cl source. Di et al.24 obtained BiOI microspheres using ionic liquid as I source at room temperature. Zhang et al.25 synthesized BiOBr lamellas using NaBr as Br source in a

INTRODUCTION Semiconductor photocatalysis as a green, sustainable treatment represents a promising approach to solve the increasing energy shortage and environmental contamination.1,2 Since Fujishima discovered that TiO2 can be used as an electrode in 1972,3 TiO2 has been commonly used as a photocatalyst to remove the organic pollutants owing to the low-cost fabrication, nontoxicity, good photostability, and excellent photocatalytic activity.4,5 Regardless of the notable advances of TiO2, the low separation rate of photogenerated electron−hole pairs and the relatively inefficient utilization of solar energy (only 4% of the solar spectrum) limit the further application.6−8 Hence, it is urgent to design efficient visible-light-driven photocatalysts to maintain environmental sustainability. To this end, great efforts have been paid to the band gap regulation and quantum efficiency improvement. In past years, series of semiconductor materials have been obtained, such as g-C3N4,9 BiWO6,10 Fe2O3,11 and AgBr.12 Nowadays, bismuth oxychloride (BiOCl), regarded as a kind of promising bismuth oxyhalide, has attracted much interest and has been used as a photocatalyst due to its outstanding © 2016 American Chemical Society

Received: August 18, 2016 Revised: December 14, 2016 Published: December 22, 2016 1416

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dark and stirred for 30 min to reach absorption−desorption equilibrium before irradiation. After a given time, 3 mL of mixture was sampled and centrifuged to remove the BiOCl materials. The RhB concentration was determined by DRS analysis according to its absorbance at 553 nm. Photoelectrochemical Measurements. The photocurrent was studied by preparing the modified electrodes in a standard threeelectrode system which included the reference electrode [Ag/AgCl (saturated KCl)), the counter electrode (Pt wire), and the working electrodes (prepared samples)]. The working electrodes were obtained by spreading 20 μL of the slurry containing 2 mg of BiOCl samples, 0.2 mL of ethanol, and 0.2 mL of EG over a fixed area of 0.5 cm2 ITO slice. A Xe arc lamp (500 W) was chosen as the light source. Phosphate buffer solution (PBS, 0.01 M, pH 7.2) was used in the photocurrent process.

hydrolysis system, while polyelectrolyte-assisted synthesis of BiOCl materials has been rarely studied. In this paper, we have successfully fabricated BiOCl materials with 3D structure using a polyelectrolyte, poly(allylamine hydrochloride), for the first time. Poly(allylamine hydrochloride) is cationically charged at neutral pH and has been applied in many fields,26,27 such as spinning, water treatment, drug intermediates, and metal finishing.28,29 Patwardhan et al.30 have fabricated nanometer and micrometer sized silica spheres by using poly(allylamine hydrochloride) at neutral pH and under ambient conditions. The role of poly(allylamine hydrochloride) is similar to the ionic liquid or poly(ionic liquid). Therefore, polyelectrolyte can be considered as the template or structure-directing agent to synthesize BiOCl. Also, the structure of as-fabricated BiOCl materials was characterized, and the effects of poly(allylamine hydrochloride) concentration on the structure of BiOCl materials were studied. This new synthesis route of BiOCl opens a window for the design and fabrication of other nanomaterials. Moreover, the BiOCl materials were used to degrade RhB under visible light irradiation. Furthermore, the structure−activity relationships as well as the mechanism of enhanced photocatalytic activity for BiOCl were studied.

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RESULTS AND DISCUSSION Structure and Morphology. The crystallographic structure of the BiOCl materials is investigated by XRD. All the peaks for the BiOCl materials were indexed to the tetragonal phase of BiOCl (JCPDS card 06-0249) with sharp and narrow reflections (Figure 1), while, compared with others, the

EXPERIMENTAL SECTION

Chemicals. All the chemicals were used without further purification. The general structure of polyelectrolyte poly(allylamine hydrochloride) (Sinopharm Chemical Reagent Co. Ltd.) is shown below:

Synthesis of BiOCl Materials. Typically, a certain amount of polyelectrolyte was dissolved in 40 mL of ethylene glycol, and 2 mmol Bi(NO3)3·5H2O was added into above solution. Then, the mixture continue stirring for 2 h. The suspension was kept at 150 °C for 24 h in a 50 mL Teflon-lined autoclave. After cooling down to room temperature, the products were washed several times with distilled water and ethanol and dried at 50 °C overnight. The as-fabricated materials were labeled as BiOCl-X, in which X represented the mass of polyelectrolyte (0.25, 0.5, 0.75, and 1.0 g). Also, the molar ratios of Cl ion to Bi ion were 1.3, 2.7, 4.0, and 5.4, respectively. Characterization. The X-ray diffraction analysis (XRD) was conducted on a Bruker D8 Advance diffractometer (Germany) with Cu Kα radiation in the 2θ range 20−80°. The morphology was analyzed by scanning electron microscopy (SEM) (JEOL JSM-5600L). Transmission electron microscopy (TEM) was taken with a JEM-2010 instrument with an accelerating voltage of 100 kV. The N2 physical adsorption and desorption isotherms were obtained by using an ASAP 2020 apparatus (Micromertics). Ultraviolet−visible diffuse reflectance spectroscopy (UV−vis DRS) measurements were carried out on a UV−vis spectrophotometer (UV-3600, Shimadzu). An ESCALab MKII X-ray photoelectron spectrometer with Mg Kα source was used to obtain X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectroscopy was measured using a fluorescence spectrometer (Shimadzu RF-5301, the sample concentration was 1 mg/mL). Photocatalytic Activity. The photocatalytic activities of asfabricated BiOCl materials were assessed by the photocatalytic decompositions of RhB (10 mg/L) under visible light irradiation. A Xe lamp (500 W) with a 400 nm cutoff filter was used to obtain visible light. In the photocatalytic experiments, the mixture of 30 mg of BiOCl photocatalyst and 100 mL of RhB solution was placed in the

Figure 1. XRD patterns of as-prepared BiOCl materials.

relatively broad and weak peaks of sample BiOCl-0.25 indicate the poor crystallinity and small size of the sample. Moreover, peak intensities of samples have an increasing tendency with the increase of polyelectrolyte concentration. It is worth noting that the diffraction intensity of [001] increases with the increase of polyelectrolyte concentration, which may be due to the formation of large lateral size oriented along the [001] direction. No additional obvious characteristic peaks were obtained, suggesting the purity of the as-fabricated BiOCl materials. Figure S1 showed the FT-IR spectra of BiOCl-0.5 and polyelectrolyte. The IR peak of BiOCl-0.5 at 3434 cm−1 is the stretching frequency for hydroxyl, and the peak at 1626 cm−1 is the bending vibration peak for hydroxy of adsorbed water. The peak of the BiOCl sample at 522 cm−1 is the Bi−O stretching vibration peak. For the sample polyelectrolyte, the 2996 cm−1 peak is the stretching vibration peak for NH3+, and that at 1528 cm−1 is the deformation vibration peak for N−H. The 1475 and 1386 cm−1 peaks are the deformation vibration peak and bending vibration peak for C−H, respectively. In addition, the 1386 cm−1 peak for C−H and 2996 cm−1 peak for NH3+ can be seen from the curve of BiOCl, indicating that the polyelectrolyte may remain in the structure of BiOCl after 1417

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Figure 2. SEM images of the BiOCl materials: (A, B) BiOCl-0.25, (C, D) BiOCl-0.5, (E, F) BiOCl-0.75, (G, H) BiOCl-1.0.

consists of individual microspheres with self-assembled flowerlike architectures whose size is about 2 μm. A typical highmagnification SEM image of Figure 2D showed the flower-like microspheres constructed from abundant nanosheets. Moreover, it can be found that the structure possesses highly geometrical symmetry except for a loose part in the sphere, while the sample BiOCl-0.75 exhibits a plate-like layered structure with self-assembled flower-like architectures in the edge of the plate with a size of about 3 μm. With the increase of polyelectrolyte, BiOCl-1.0 also shows a plate-like layered structure whose size is about 5 μm. It is known that the edges of layered structured materials have many atoms with

washing with water and alcohol. Due to the high peak intensity of BiOCl, the characteristic peak at 25° for polyelectrolyte which indicates the amorphous structure of the polyelectrolyte may not be noticed in XRD results (Figure S2). The morphology of the BiOCl synthesized with different polyelectrolyte concentrations was visualized by SEM. It is known that agglomeration of nanoparticles can influence the surface activity of materials. As is shown in Figure 2, all the samples are monodispersed, which may be beneficial for improving the photocatalytic ability of samples. As for the sample BiOCl-0.25, an irregular flower-like structure can be found. Compared with BiOCl-0.25, the sample BiOCl-0.5 1418

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to the function of ionic liquid or poly(ionic liquid). At the low electrolyte content, the electrolyte tends to form the sphere-like micelles, and then three-dimensional BiOCl microspheres which consist of nanosheets are obtained. With the increase of the electrolyte content, the sphere-like micelles change into the layered morphology, resulting in the formation of the platelike BiOCl materials. Due to the edges of layered structured materials having many atoms with dangling bonds, the layered materials are inclined to form curved plates to saturate the dangling bonds and minimize the total surface energy. The formation process of BiOCl materials is shown in Figure 4. The thermal stability of an as-prepared BiOCl-0.5 sample, which is an important factor for catalysts, has been studied. Also, the result is exhibited in Figure S3. It is found that there is a little weight loss (about 2%) before 270 °C, which may be ascribed to the loss of absorbed water or the polyelectrolyte with a small molecule. Also, the weight of the sample has an obvious decrease from 270 °C, which may be the decomposition for the NH3+Cl− of the polyelectrolyte. Moreover, there is a sharp decrease from 460 °C, reflecting the decomposition of BiOCl-0.5 sample and the further decomposition of polyelectrolyte. It is found that the weight loss of BiOCl-0.5 is about 43% when the temperature increases to 800 °C. The peaks at about 570 and 750 °C in the DSC curve represent the decomposition of polyelectrolyte and the further decomposition of polyelectrolyte and BiOCl-0.5, respectively, which correspond to the TG curve. The TG analysis certifies the presence of polyelectrolyte, which is consistent with the results of FT-IR. N2 gas sorption was used to obtain the BET surface area and adsorption−desorption isotherm. From Figure 5, a pronounced hysteresis loop can be found at high P/P0, proving the existence of macropores. In addition, the specific surface areas of BiOCl0.25 and BiOCl-0.5 are 5.6 m2/g and 3.0 m2/g, respectively, which is larger than plate-like BiOCl-0.75 (2.5 m2/g) or BiOCl1.0 (2.1 m2/g) because of the plate-like structures for BiOCl0.75 and BiOCl-1.0 (Figure S4). In a comparison with the BiOCl nanosheets (5.53 m2/g) obtained by Haider et al.,32 the BiOCl microspheres possess similar large specific surface areas. Also, the special structure and larger specific surface area of BiOCl materials may be good for the adsorption of the substrates and photocatalytic activity. Photocatalytic Activity. The photocatalytic activities of the as-fabricated BiOCl materials were evaluated by degrading RhB under visible light irradiation (Figure 6). From the blank experiment without photocatalyst, it is known that the

dangling bonds. The layered materials are inclined to form curved plates to saturate the dangling bonds and minimize the total surface energy, which is consistent with the previous work.31 Therefore, the polyelectrolyte plays an important role for the morphology of BiOCl during the reactive process, and the materials’ particle size increases with the increase of polyelectrolyte. The polyelectrolyte not only acts as the reactant but also acts as the template at the same time. Figure 3 shows the TEM images of BiOCl materials. From the TEM images, the layered structure of the materials can be

Figure 3. TEM images of BiOCl samples: (A) BiOCl-0.25, (B) BiOCl0.5. The inset is the diffraction ring of the sample (C) BiOCl-0.75, (D) BiOCl-1.0.

clearly found. Moreover, the flower-like BiOCl microspheres consisted of abundant nanosheets. Also, the diffraction ring of BiOCl-0.5 indicates the good crystallinity of the sample. In addition, the TEM images give evidence that the size becomes large with the increase of polyelectrolyte content. For the synthesis of BiOCl materials with different morphologies, the polyelectrolyte plays a critical role. The electrolyte not only acts as reactant, but also acts as a soft template during the process of the experiment, which is similar

Figure 4. Schematic illustration of the formation for BiOCl microspheres and plate-like BiOCl. 1419

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BiOCl-0.25 possesses the maximum k of 0.0185 min−1, which is about 1.03 times, 3.08 times, 11.56 times, and 13.70 times as high as that of BiOCl-0.5, BiOCl-0.75, BiOCl-1.0, and g-C3N4, respectively. Di et al.30 found that the maximum k of 0.0238 min−1 can be obtained in the degradation of RhB with the addition of 50 mg of BiOI hollow microspheres. Regardless of the similar rate constant, only 30 mg of BiOCl photocatalyst was used in our experiments, which was much lower than that of their work. In a comparison with this kind of photocatalyst, as-fabricated BiOCl-0.5 possessed enhanced catalytic activity, because of the monodispersed structure. The rate constants of all the materials are shown in Table S1. To investigate the stability of the photocatalyst BiOCl-0.5, we carried out the recycling experiments for the degradation of RhB under the visible light irradiation. With respect to Figure 7, Figure 5. Nitrogen adsorption−desorption isotherm of BiOCl-0.5 microspheres.

degradation of RhB without catalysts can almost be neglected, which is in agreement with the literature.24,33 The BiOCl-0.25 sample shows higher activities than that of other samples. The RhB degradation rate of BiOCl-0.25 can reach 98.1% under visible light irradiation for 195 min, and BiOCl-0.5 has the similar RhB degradation rate (97.5%) for the same irradiation time. Compared with the samples BiOCl-0.25 and BiOCl-0.5, the RhB degradation rate of BiOCl-0.75, BiOCl-1.0, and gC3N4 can just approach 69.7%, 33.1%, and 23.1% after 195 min, respectively. Thus, BiOCl materials with flower-like microspherical structure have the advantage in the degradation of RhB, which may be related to the high surface area and relatively small size of the materials. Figure S5 shows the UV− vis absorption spectra of the RhB photocatalytic degradation by BiOCl materials. A decrease in the 553 nm peak can be clearly seen, with a blue shift in the absorption band, which is due to the step-by-step de-ethylation process.33 The data is replotted on the basis of the pseudo-first-order kinetic model to quantitatively know the reaction kinetics of RhB degradation over different samples. ln(C0/C) = kt

Figure 7. Cyclic photocatalytic degradation experiments of RhB by flower-like BiOCl-0.5.

there is no obvious decrease in the photocatalytic activity after four cycles, which gives evidence that as-prepared BiOCl-0.5 material is very stable during the degradation experiments. Also, microsized structure is convenient for recovery from the solution, which may be beneficial to the high stability to a certain degree. From the results of RhB degradation, it can be obtained that BiOCl materials exhibit enhanced photocatalytic activities, which is related to the adsorption capacities of materials and

(2)

In the above equation, the following appreviations are used: k is the rate constant, t is the irradiation time, and C0 and C are the concentrations of RhB when time is 0 and t, respectively. The

Figure 6. Photocatalytic activities (A) and kinetics (B) of the as-fabricated BiOCl materials for degradation of RhB. 1420

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ACS Sustainable Chemistry & Engineering the conduction band (CB) of BiOCl. Moreover, the adsorption is more important than the conduction band of BiOCl for the degradation.15 Thus, the RhB adsorption capacities of BiOCl materials are studied. Also, the results are shown in Figure 8. It

Figure 9. UV−vis diffuse reflectance spectra of the as-fabricated BiOCl materials. Figure 8. RhB adsorption capacities of BiOCl materials.

the O atoms around an O-vacancy. Moreover, the sample BiOCl-0.25 possesses many more O-vacancies than BiOCl0.75. With respect to BiOCl-0.25 with more O-vacancies, the electrons can easily be excited into the conduction band under visible light irradiation, accordingly obtaining the significantly enhanced photocatalytic activity, indicating the important role of O-vacancies in improving photocatalytic activity.35 Figure 11 shows the PL spectra of BiOCl materials at an excitation wavelength of 360 nm. Through the PL spectra, the recombination rate of photogenerated electrons and holes can be obtained. The 3D structure BiOCl-0.25 displays the lower PL intensity than other samples, indicating the O-vacancies may be good for the separation of photogenerated electrons and holes. Moreover, the intensity of the flower-like BiOCl-0.5 sample is lower than that of the plate-like layered structure BiOCl-0.75. From the SEM images, it is found that the microsphere consists of nanosheets. Also, the excellent interface contact is beneficial to the faster interfacial charge transfer. In addition, O-vacancies can act as the active sites to improve the carrier separation effiency, which is in agreement with the XPS analysis results. Electrochemistry Analysis. Transient photocurrent response for the BiOCl materials is shown in Figure 12. It is known that the photocurrent of the ITO electrode can be ignored.30 In addition, the photocurrent intensity of BiOCl0.25 is similar to that of BiOCl-0.5, which is consistent with the photocatalytic activity analysis. The intensity of flower-like BiOCl-0.5 was 2.5 times or 3 times higher than that of plate-like BiOCl-0.75 and BiOCl-1.0, respectively. The result indicates that the BiOCl-0.25 and BiOCl-0.5 have the more efficient utilization of the solar-light resource than plate-like BiOCl-0.75 and BiOCl-1.0, which may be related to the large surface area of BiOCl microspheres. Proposed Mechanism. Trapping experiments of active species are carried out to determine the reactive active species generated during the photocatalytic degradation of RhB over BiOCl-0.5 materials under visible light irradiation. In the experiment, EDTA-2Na and dimethylcarbinol (IPA) were used as the scavengers of holes as radical and hydroxyl radical, respectively. As shown in Figure 13, the photocatalytic degradation of RhB by BiOCl-0.5 is not influenced by the addition of IPA, while the addition of EDTA-2Na significantly

is known that the mixtures containing the as-fabricated photocatalysts and RhB should be stirring in the dark for 30 min before visible light irradiation to guarantee the dye is adsorbed on the surface of photocatalysts. As is shown in Figure 8, the sample BiOCl-0.25 possesses the highest adsorption capacity among the as-fabricated materials, as high as 24.7%. Also, the adsorption capacity of BiOCl-0.5 (23.1%) is also significantly higher than that of BiOCl-0.75 (16%) and BiOCl (12.2%) nanoplates, which may be attributed to the larger surface area of flower-like BiOCl microspheres than plate-like BiOCl materials. In addition, the adsorption results also certify the high photocatalytic activity of flower-like BiOCl0.25 and BiOCl-0.5 samples. Moreover, FT-IR analysis was applied to characterize the adsorption ability of BiOCl (Figure S6). The corresponding characteristic peaks of RhB can be seen from the curve of BiOCl-0.5/RhB which was obtained after magnetically stirring in the dark for 30 min. This gives evidence for the existence of RhB on the surface of the catalyst BiOCl. The optical absorptions of BiOCl materials as an important role for photocatalytic performance are analyzed. As is shown in Figure 9, BiOCl materials exhibit strong absorption intensity from 200 to 500 nm with the obvious absorption edge around 500 nm, indicating that the band gap is narrower than 2.4 eV. Moreover, the absorption edge of flower-like material is a little larger than that of plate-like material. The relatively large surface area of a sphere may be conducive to the excellent visible light absorption ability. Furthermore, the microspheres consist of nanosheets, which contribute to the faster interfacial charge transfer. Also, the intensity of the absorbance of BiOCl decreases with the increasing polyelectrolyte content during the synthesis process. The enhanced light harvesting in the visible light range and the narrow band may also be ascribed to the presence of oxygen vacancies. It is found that O-vacancies in oxide semiconductors can act as the active sites for improving the carrier separation efficiency, therefore narrowing the band gap and enhancing the photocatalytic activity.34 To shed light on the relation between O-vacancies and photocatalysis, the XPS of flower-like BiOCl-0.25 and plate-like BiOCl-0.75 are studied. As can be seen from Figure 10B, two peaks can be found: one peak at 528.6 eV is attributed to the oxygen in BiOCl materials, and the other at 531.6 eV may be deemed as 1421

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Figure 10. XPS spectra of BiOCl materials: (A) full scan, (B) O 1s, (C) Cl 2p, (D) Bi 4f.

Figure 11. PL spectra of BiOCl materials.

Figure 12. Transient photocurrent response for the BiOCl materials.

affects the photocatalytic activity, implying that the main active species in the system are the holes. On the basis of the above results, we know that several factors including the morphology, high surface area, Ovacancies, and low recombination rate of photogenerated electron−hole pairs contribute to the enhanced photocatalytic activities of flower-like BiOCl microspheres.

solvothermal method. The influence of polyelectrolyte concentrations on the formation of BiOCl was systematically investigated. The polyelectrolyte, which acted as reactant, template, or structure-directing agent, was critical to the structure of as-fabricated BiOCl materials during the reactive process. The different morphologies can be obtained under different polyelectrolyte contents. At low polyelectrolyte content, BiOCl microspheres were obtained. Also, plate-like BiOCl species were synthesized at higher polyelectrolyte concentration. The possible formation mechanism of the BiOCl materials had been studied. Moreover, the photocatalytic activity of as-prepared BiOCl microspheres was higher than

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CONCLUSIONS In summary, the reactable polyelectrolyte, poly(allylamine hydrochloride), was used as the template for the first time to fabricate BiOCl materials with different morphology by using a 1422

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Central Universities (3207045421, 3207046302, 3207046409), and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) (1107047002).

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Figure 13. Photocatalytic degradation of RhB over BiOCl-0.5 materials with the presence of scavengers.

those of plate-like BiOCl materials. From the trapping experiments of active species, the holes rather than •OH were the predominant active species during the RhB degradation process by using as-prepared BiOCl materials. In addition, the special structure, high surface area, O-vacancies, lower recombination rate of photogenerated electron−hole pairs, enhanced adsorption capability of dye, and faster interfacial charge separation had contributed to the good photocatalytic activity and high photostability of BiOCl microspheres. This work provides a new approach to prepare BiOCl materials with polyelectrolyte for use in environmental protection.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b01987. FT-IR spectra, XRD patterns, TG analysis, nitrogen adsorption−desorption isotherm of BiOCl materials, absorption profiles, and pseudo-first-order rate constants (PDF)

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REFERENCES

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. Phone: +86 25 52090617. Fax: +86 25 52090617. *E-mail: [email protected]. ORCID

Shuo Zhao: 0000-0002-6565-7172 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The work was supported by National Natural Science Foundation of China (Grants 21676056, 21376051, 51673040, and 21306023), “Six Talents Pinnacle Program” of Jiangsu Province of China (JNHB-006), Natural Science Foundation of Jiangsu Province (Grant BK20131288), Fund Project for Transformation of Scientific and Technological Achievements of Jiangsu Province of China (Grant BA2014100), Qing Lan Project of Jiangsu Province (1107040167), The Fundamental Research Funds for the 1423

DOI: 10.1021/acssuschemeng.6b01987 ACS Sustainable Chem. Eng. 2017, 5, 1416−1424

Research Article

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DOI: 10.1021/acssuschemeng.6b01987 ACS Sustainable Chem. Eng. 2017, 5, 1416−1424