Three dimensional BiOX (X=Cl, Br and I) hierarchical architectures: facile ionic liquid-assisted solvothermal synthesis and photocatalysis towards organic dye degradation

doi:10.1016/j.matlet.2013.03.045

Materials Letters

Volume 100, 1 June 2013, Pages 285-288

https://doi.org/10.1016/j.matlet.2013.03.045 Get rights and content

Highlights

•
High-crystalline hierarchical BiOX (X=Cl, Br and I) microspheres were prepared.
•
The BiOX (X=Cl, Br and I) microspheres are assembled by numerous interlaced nanosheets.
•
Choice of solvent plays an important role in determining the BiOI morphologies.
•
BiOI hierarchical microspheres with smallest band gap exhibited superior photocatalytic efficiency.

Abstract

High-crystalline hierarchical BiOX (X=Cl, Br and I) microspheres were prepared by a generalized ionic liquid-assisted solvothermal method. The as-prepared BiOX (X=Cl, Br and I) microspheres were uniform in size and the average diameters ranged from one to several micrometers, which were assembled by numerous interlaced nanosheets. According to the UV–Vis diffuse reflectance spectra, the band gaps were calculated to be 3.20, 2.72 and 1.76 eV for the BiOCl, BiOBr and BiOI samples, respectively. Evaluated by the decomposition of methyl orange (MO) solution, the BiOI product exhibited much better photocatalytic efficiency to BiOCl and BiOBr samples, which could respond to more visible light as well as facilitate the spatial transfer of the photoexcited carriers.

Graphical abstract

Introduction

As an important kind of V–VI–VII main group ternary semiconductors, bismuth oxyhalides BiOX (X=Cl, Br and I) crystallize in layered structures comprising of [Bi₂O₂]²⁺ slabs interleaved with double halide atoms layers. Such intrinsic layered structures give rise to the highly anisotropic electrical, magnetic and optical features, which make bismuth oxyhalides promising in industrial applications such as pharmaceuticals, organic catalysts and pigments [1], [2], [3]. Recently, bismuth oxyhalides have also been discovered to show excellent photocatalytic activity in wastewater and indoor air purification [4], [5], [6], [7], [8]. For example, Zhang and co-workers have studied the BiOCl photocatalyst and found that its photocatalytic performance in the degradation of MO was better than the standard TiO₂ (P25, Degussa) under UV irradiation [4]. Ai and co-workers reported that the BiOBr microspheres displayed efficient photocatalytic removal of textile NO species in indoor air [5]. Up to now, a variety of BiOX (X=Cl, Br and I) nano-/microstructures, such as nanoparticles [9], nanobelts or nanofibers [10], [11], nanoplates or nanosheets [12], [13], [14], [15], and microspheres [16], [17], [18], have been prepared. In spite of much progress, the development of morphological multiplicity is crucial for the photocatalytic applications, and the generalized synthetic protocol range is also required to be expanded. In addition, it is of great practical significance to boost the photocatalytic performances of bismuth oxyhalides by rational microstructure regulations.

Herein, we have systematically synthesized three dimensional BiOX (X=Cl, Br and I) hierarchical microspheres by the generalized ionic liquid-assisted solvothermal method, which are constructed by interlaced nanosheets. The role of the reactant solvent in determining the microstructures of BiOI was also studied. Evaluated by the decomposition of MO dye under visible light irradiation, the as-prepared BiOI hierarchical microspheres showed the best photocatalytic activity.

Section snippets

Experimental section

Halide-containing ionic liquids (ILs) such as 1-hexadecyl-3-methylimidazolium chloride ([C₁₆Mim]Cl), 1-hexadecyl-3-methylimidazolium bromide ([C₁₆Mim]Br) and 1-hexyal-3-methylimidazolium chloride ([C₆Mim]I) were used as Cl, Br and I sources, respectively. Briefly, Bi(NO₃)₃·5H₂O (2 mmol) and [C₁₆Mim]Cl (3 mmol) were separately dissolved in 40 mL of 2-methoxyethanol and mixed together. The suspension was stirred and transferred into a 100 mL autoclave. The autoclave was heated and maintained at 160 °C

Results and discussion

Fig. 1 displays the SEM images of the BiOX (X=Cl, Br and I) hierarchical microspheres. Nevertheless, 2-methoxyethanol was used as the solvent for the preparation of BiOCl and BiOBr hierarchical architectures, while ethylene glycol was used for the BiOI ones. As shown in Fig. 1, all the as-prepared BiOX (X=Cl, Br and I) samples are hierarchical microspheres constructed by numerous two dimensional interlaced nanosheets with thickness of 10–20 nm. The average diameters are in the range of 1.5–2.5,

Conclusions

In summary, we have successfully synthesized three dimensional BiOX (X=Cl, Br and I) hierarchical microspheres with high crystallinity. The as-prepared microspheres were uniform with sizes in the range of several micrometers and assembled by numerous two dimensional interlaced nanosheets. It is found that BiOI hierarchical microspheres with the smallest band gap showed the best photocatalytic performance under visible light irradiation. This work illustrates a solution-based route to

Acknowledgement

This work was financially supported by the National Basic Research Program of China (973 program, No. 2013CB632401).

References (22)

N. Kijima et al.
Appl Catal A—Gen
(2001)
K.L. Zhang et al.
Appl Catal B—Environ
(2006)
C.H. Wang et al.
Scr Mater
(2008)
G.G. Briand et al.
Chem Rev
(1999)
H.L. Peng et al.
Chem Mater
(2009)
Z.H. Ai et al.
Environ Sci Technol
(2009)
H.F. Cheng et al.
Chem Commun
(2011)
H.F. Cheng et al.
Chem Commun
(2012)
Y.Y. Liu et al.
Chem Eur J
(2011)
J. Henle et al.
Chem Mater
(2007)

H. Deng et al.

Chem—Eur J

(2005)

Cited by (128)

Metal doped BiOCl nano-architectures (M-BiOCl, M = Ni, Mo, Cd, Co) for efficient visible light photocatalytic and antibacterial behaviour
2023, Journal of Environmental Chemical Engineering
Herein, we report the fabrication of well-crystalline metal (Ni, Mo, Cd and Co) doped BiOCl nanoscale photocatalytic material (M-BiOCl; M = Ni, Mo, Cd, and Co) by employing the solvothermal synthetic route. It was found that Ni doping results in remarkable improvement in photocatalytic and antibacterial behavior of BiOCl. The morphological investigation of typical samples by the FE-SEM revealed that undoped BiOCl shows closely stacked thick discs like morphology, while doping with different metals resulted into nanosheet (Ni, Cd), nanoflowers (Mo) and nanodiscs (Co) like morphologies. Interestingly, doping of Ni metal led to a substantial transformation into large size nanosheets with (010) prominent facet and increased surface area (41.927 m²/g) along with improved porous structure. Similarly, HR-TEM confirmed the formation of extended nanosheet like growth having dimensions ∼287.16 × 179.14 nm for Ni-BiOCl photocatalyst along with nano-pores morphology that might serve as active sites during photocatalysis or antibacterial activity. Moreover, the inclusion of Ni into BiOCl nanostructure brings the band gap (Eg) shifted to 2.85 eV from 3.54 eV (pure BiOCl), while all other metal doped nanostructure exhibited nearly similar Eg. Meanwhile, the photo-induced charge carriers recombination behaviour analysed by photoluminescence (PL) analysis shows diminished peak intensity for Ni-BiOCl as compared to pure BiOCl that can be directly correlated with minimum recombination of electron-hole during photocatalysis thus contributing for its excellent photocatalysis performance. In addition, we observed the excellent photocatalytic antibacterial activity of Ni-BiOCl against S. aureus bacteria under the visible light.
Myth or reality? A disquisition concerning the photostability of bismuth-based photocatalysts
2022, Journal of Environmental Chemical Engineering
Photocatalysis is a well-known and extensively investigated field within advanced oxidation processes. Numerous papers have been reported that the semiconductors applied were photostable and potentially reusable based on the degradation efficiencies observed. However, researchers did not attach enough importance to investigate the residual catalysts in most cases. Here, we report on some important alterations that occurred during photocatalytic experiments, such as acid-induced and light-assisted structure break-down and complete transformation of catalysts, which could place their photostability into a new perspective. In this work, the photostability of five, increasingly popular bismuth-based oxides (Bi₂WO₆, BiVO₄, BiOI, BiOCl, and BiOBr) were investigated in the presence of various carboxylic acids (oxalic acid, formic acid, salicylic acid, malonic acid, and ascorbic acid), focusing on the crystallographic and morphological alterations of the residual photocatalysts. When investigating the resistance of the photocatalysts to oxalic acid, the formation of bismuth oxalate hydroxide was observed in all cases. At the same time, most components of the catalysts appeared in the liquid phase in high amounts. Similar transformations occurred to a lesser extent for the other acids, which was deduced to be related to the acidic strength and proton concentration. We also highlighted that in some instances, during photocatalytic processes, the occurrence of light-assisted acid-induced reactions must be considered as well.
Simultaneous photocatalytic oxidation and adsorption for efficient As(III) removal by magnetic BiOI/γ-Fe<inf>2</inf>O<inf>3</inf> core–shell nanoparticles
2022, Materials Today Chemistry
Addressing arsenite pollution in groundwater has drawn great attention. It is attractive to pre-oxidize highly mobile As(III) to relatively low-toxic As(V) with a subsequent adsorption separation process. Herein, BiOI anchoring on γ-Fe₂O₃ is performed to synthesize BiOI/γ-Fe₂O₃ core–shell nanoparticles for efficient removal of As(III) via a simultaneous photocatalytic oxidization–adsorption process. The physical and chemical structures of BiOI/γ-Fe₂O₃ are investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction measurements. The photoluminescence and electron spin resonance (ESR) characterization were employed to ascertain the possible reaction mechanism of visible-light-driven photocatalytic oxidation of As(III). Such BiOI/γ-Fe₂O₃ delivers a superior As(III) removal capability under visible light irradiation with an arsenic removal efficiency of 99.8% within 180 min, higher than those of BiOCl/γ-Fe₂O₃ (81.7%) and BiOBr/γ-Fe₂O₃ (98.9%). The optimal BiOI/γ-Fe₂O₃ (molar ratio of 2:1) is obtained by rationally adjusting the molar ratio of BiOI to γ-Fe₂O₃. The as-synthesized BiOI/γ-Fe₂O₃ performs well in a wide pH range of 2–8. Only coexisting PO₄³⁻ anions have a significant effect on the As(III) removal. The free radical trapping experiment and ESR results demonstrate that the ⋅O₂⁻ and h⁺ are the main active substances for the photocatalytic oxidation of As(III) on BiOI/γ-Fe₂O₃. This work not only gives a novel magnetic core–shell nanoparticle photocatalyst for efficient photocatalytic oxidation and adsorption of As(III) but also offers a new strategy to rationally design BiOX for its related practical applications.
Improving photocatalytic activity under visible light over a novel food wastes biochar-based BiOBr nanocomposite
2022, Chemosphere
Biochar (C) applied in synthesizing photocatalysts to eliminate water pollution has been intensively investigated. Herein we report the first use of biochar pyrolyzed from food wastes at 400 ^°C (400C) and 700 ^°C to construct C/BiOBr composites via a facile hydrolysis approach. Photocatalytic performances could be significantly improved by choosing the appropriate carbonization temperature and adjusting the content of C in C/BiOBr composites. The prepared 1%400C/BiOBr exhibited the best photodegradation capacity towards methylene orange (20 mg/L) and tetracycline (50 mg/L). A series of characterization results illustrated that smooth structure and surface properties (oxygen functional groups and persistent free radicals) of 400C played an important role in enhancing the photocatalytic activities. Mechanism exploration suggested that h⁺ and ˙O₂⁻ were the main active species thus contributing to photodegradation. This study provided a new insight into utilization of biochar derived from food wastes in photocatalysis and environmental remediation.
Design and synthesis of α-Bi<inf>2</inf>Mo<inf>3</inf>O<inf>12</inf>/CoSO<inf>4</inf> composite nanofibers for high-performance SO<inf>2</inf>F<inf>2</inf> sensors at room temperature
2022, Materials Today Nano
We introduce a generic, facile, and environment-friendly strategy to fabricate a flexible, low-cost, highly sensitive nanocomposite by incorporating electrospinning and hydrothermal process with a self-powered sensor device that contributes toward a better and safer life. Our research work based on the novel composite α-Bi₂Mo₃O₁₂/CoSO₄ operating at room temperature shows fascinating ability to improve the long-term sensitivity and stability of gas sensors and a reduced cost of operation. This novel composite sensor offers a unique combination of features to overcome the major challenges, especially in gas sensor applications, and can guarantee rapid progress spanning over academic and industrial domains. The composite-based α-Bi₂Mo₃O₁₂/CoSO₄ sensor showed an improvement in high sensitivity and response speed owing to the porous active site of the materials to the target gas SO₂F₂ at RT. The porous nature of the CoSO₄ nanoparticle-loaded α-Bi₂Mo₃O₁₂ nanofibers improved their surface area from 33.3 m²/g to 173 m²/g, which was confirmed by Brunauer-Emmett-Teller resulting in high haze especially in the S₃ sample. This can dramatically boost up sensor response up to ∼2970% at RT with a low detection range of 100 ppm SO₂F₂. Particularly, composite-based sensors α-Bi₂Mo₃O₁₂/CoSO₄ exhibit high sensitivity, excellent stability, mild response/recovery times (τ_res = 193 s and τ_res = 319 s), and good durability/repeatability without any power consumption. This results in a potential and versatile mechanical sensor that will pave the way for online monitoring to address environmental and industrial challenges. The resulting composite material can be applied to a polyamide substrate to obtain a flexible and smart sensor that could provide a technical roadmap for the next wave of sulfur hexafluoride (SF₆) innovations and breakthroughs.
ZIF-8 derived ZnO–calcium silicate mesoporous structures: Synthesis and photocatalytic activity
2022, Microporous and Mesoporous Materials
Citation Excerpt :
Interestingly, it was noted that the MB was photodegraded slower than RhB despite its higher adsorption onto ACS. This phenomenon is possibly attributed to the most positive LUMO level of RhB molecules compared with MB [41–43]. On the other hand, both ACS@ZnO (2.7%) and pure ZnO (0.8%) showed poor adsorption properties towards MO (Fig. 6e) due to the anionic nature of the MO molecules.
Nanoscale metal-organic frameworks (MOFs) show potential as catalysts or catalyst precursors, but they suffer from difficult separation and weak stability and do not conform to practical application conventions. Herein, we demonstrate the application of nanostructured calcium silicate hydrate (C–S–H), the building block of Portland cement concrete, to fabricate hierarchically porous zeolitic-imidazolate-framework-8 (ZIF-8)-derived ZnO nanocomposites. The dispersing and stabilizing effects of the C–S–H nanoplate structure effectively suppressed the agglomeration of ZIF-8 nanocrystals during high-temperature treatment. After calcination at 450 °C, ZnO nanocomposites with high specific surface area (579 m² g⁻¹) and hierarchical porosity were obtained. The nanocomposites were used as photocatalysts for degradation of rhodamine B and exhibited degradation efficiency as high as 95.5% within 45 min of UV light illumination with high photocatalytic stability and excellent reusability. This study demonstrated a facile way of using economic and versatile C–S–H nanostructures to fabricate MOF and MOF-derived nanocomposites with enhanced stability and functionality.

View all citing articles on Scopus

View full text

Three dimensional BiOX (X=Cl, Br and I) hierarchical architectures: facile ionic liquid-assisted solvothermal synthesis and photocatalysis towards organic dye degradation

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Experimental section

Results and discussion

Conclusions

Acknowledgement

Appl Catal A—Gen

Appl Catal B—Environ

Scr Mater

Chem Rev

Chem Mater

Environ Sci Technol

Chem Commun

Chem Commun

Chem Eur J

Chem Mater

Chem—Eur J