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Proceeding Paper

Influence of Ionic Liquids Assisted Synthesis on Morphology and Photocatalytic Properties of Bi4O5Br2 †

Patrycja Wilczewska
Aleksandra Bielicka-Giełdoń
Agnieszka Fiszka Borzyszkowska
Aleksandra Pieczyńska
Ewa Maria Siedlecka
Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland
Author to whom correspondence should be addressed.
Presented at Innovations-Sustainability-Modernity-Openness Conference (ISMO’19), Bialystok, Poland, 22–23 May 2019.
Proceedings 2019, 16(1), 26;
Published: 25 June 2019
(This article belongs to the Proceedings of Innovations-Sustainability-Modernity-Openness Conference (ISMO’19))


A series of Bi4O5Br2 photocatalysts were prepared via an innovation method of synthesis with ionic liquids (ILs). The crystal structures were investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The Field Emission Scanning Electron Microscope (FE-SEM) images illustrated the unique structure of prepared photocatalysts. The photocatalysts were also characterized by N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis/DRS) and photoluminescence spectra (PL). The role of ILs in synthesis of Bi4O5Br2 on morphology and photocatalytic properties were investigated. Rhodamine B, 5-fluorouracil and chromium (VI) were used as the model micropollutants to evaluated adsorption capacity, photooxidation and photoreduction ability of prepared Bi4O5Br2 under artificial solar light. This work provided a new thought for enhanced photocatalytic activity of bismuth oxybromide photocatalysts.

1. Introduction

Ionic liquids (ILs) are a very wide group of compounds with unusual properties, which includes: negligible vapor pressure, good thermal stability, high ionic conductivity, broad electrochemical potential windows, good solubility and high synthetic flexibility [1]. Additionally, the interaction occurring in these compounds caused that ILs can be used in the synthesis of micro and nanomaterials [2]. Nowadays, ionic liquids were used as a solvent [3], structure-directing agents [1], templates [2] and reactants [2,4] in the preparation of unique morphology of various catalysts.
Bismuth oxybromides (BiOBr) are crystallized in a tetragonal matlockite structure, they possessed the layered structure that are composed of [Bi2O2] slabs interleaved with double halogen bromides atom slabs along the (001) direction. The layered structure is beneficial for separation of photogenerated hole-electron pairs. Thus, BiOBr has attracted wide research attention due to its suitable band-structure and high photocatalytic activity under visible light [5]. Density functional theory (DFT) calculation shows that the valence band (VB) of BiOBr is composed of hybrid orbitals of Br 4p and O 2p, and the conduction band (CB) consist of Bi 6p orbitals. More recently, it has been found that bismuth rich oxybromides had lower the semiconductor valence band position, which decreases the band gap and increases utilization of visible light and consequently, higher photocatalytic activity in this range of irradiation [6]. Aim of the research was to evaluate influence of ILs on morphology and photocatalytic activity of Bi4O5Br2 toward water micropollutants under artificial solar irradiation. In this research Bi4O5Br2 were prepared via innovative route of synthesis with ionic liquids as a bromide source, dispersing agent and template.

2. Materials and Methods

2.1. Synthesis of Bi4O5Br2

Photocatalysts were prepared via solvothermal methods in glycerol as a reaction solvent. Solvothermal reaction conducted in 50 mL Teflon reactor for 16 hours in 160 °C. The obtained precipitate was dried at 80 °C under air atmosphere. Then, the hydrolytic process were carried out. 0.3 g powder was dispersed in 100 mL deionized water and kept continuously stirring for 2 h. The photocatalysts were obtained after centrifugation, washed with deionized water and dried at 80 °C under air atmosphere. Ionic liquids which contains imidazolium (im), pyridinium (py) and pyrrolidinium (pyr) as a cations and bromides as anions were used as a source of Br- to prepared series of Bi4O5Br2. The reference sample was bismuth oxybromide synthesized from simple inorganic salt KBr without ionic liquid [4].

2.2. Photocatalytic Tests

Photocatalytic activity were evaluated by photoreduction of Cr (VI), photooxidation of rhodamine B and 5-fluorouracil under artificial solar light. In the experiment, 0.2 gL−1 of prepared Bi4O5Br2 were suspended in 15 mL of 15 mgL−1 Rhodamine B and 5-fluorouracil aqueous solution. Concentration of Cr (VI) was 20 mgL−1 and pH was adjust to 3. Before irradiation starts, the solutions mixed with photocatalysts were kept in the dark for 30 min to allow the adsorption-desorption equilibrium to be reach. The irradiation lasted 120 min and the source of light were medium pressure Hg lamp 150 W.

3. Results

The morphology of synthesized series of photocatalysts was different and ionic liquids had significant influence on the shapes and structures of the samples. Specific surfaces area of Bi4O5Br2_ils were higher than the reference Bi4O5Br2 obtained from KBr. XRD analysis confirmed pure Bi4O5Br2 phase in all samples. XPS revealed that Bi4O5Br2 photocatalysts were composed with Bi, O and Br. Obtained energy binding suggested trivalent oxidation state of bismuth and monovalent state of bromide. FT-IR analysis confirmed absence of ionic liquids on photocatalysts surface. No characteristic absortion peaks (N-C band vibrations from Ils) were observed. Obtained results were in acordance with XPS analysis.

3.1. Photocatalytic Activity

The photocatalytic activities of Bi4O5Br2 samples were measured in degradation of Rhodamine B, 5-fluorouracil and chromium (VI) in acidic solution under artificial solar irradiation. The obtained results were shown in Figure 1.
A blank experiment without prepared photocatalysts indicated that 5-fluorouracil and Cr (VI) were not degraded while Rhodamine B decomposed in no more than 20% after 120 min of irradiation. The photocatalytic degradation kinetics of Cr (VI), rhodamine B and 5-fluorouracil was pseudo-first order. For rhodamine B, the most active photocatalysts were Bi4O5Br2_py and Bi4O5Br2_pyr which were characterized the high sorption capacity. The 5-fluorouracil degradation rate under Bi4O5Br2_py was the fastest. Efficiency of Cr (VI) photoreduction was similar for all prepared photocatalysts.

4. Conclusions

The beneficial influence of ionic liquids used in the solvothermal synthesis on the morphology, structure and optical properties of the bismuth semiconductors was improved. The ILs caused loosening of the structure and increasing the particle size of semiconductors which had favorable impact on specific surface area and pore volume. The results indicate that ionic liquids applied as a halogen source can increase the photocatalytic activity of bismuth oxyhalides in micropollutants degradation.

Author Contributions

A.B.-G. and E.M.S. conceived and designed the experiments; P.W. and A.F.B. performed the experiments; A.B.-G. and P.W. analyzed the data; A.B.-G., A.P., E.M.S. contributed reagents/materials/analysis tools; A.B.-G. and P.W. wrote the paper.


This work was supported by the National Science Center within program MINIATURA 1 (DEC-2017/01/X/ST5/01136), Sonata 10 (2015/19/D/ST5/00710) and DS530-8626-D596-18.

Conflicts of Interest

The authors declare no conflict of interest.


  1. He, Z.; Paschalis, A. Ionic liquid and nanoparticle hybrid systems: Emerging applications. Adv. Colloid Interface Sci. 2017, 244, 54–70. [Google Scholar] [CrossRef] [PubMed]
  2. Ye, L.; Su, Y.; Jin, X.; Xie, H.; Zhang, C. Recent advances in BiOX (X = Cl, Br and I) photocatalysts: synthesis, modification, facet effects and mechanisms. Environ. Sci. Nano 2014, 1, 90–112. [Google Scholar] [CrossRef]
  3. Duan, X.C.; Ma, J.M.; Lian, J.B.; Zheng, W.J. The art of using ionic liquids in the synthesis of inorganic nanomaterials. CrystEngComm 2014, 16, 2550–2259. [Google Scholar] [CrossRef]
  4. Bielicka-Giełdoń, A.; Wilczewska, P.; Malankowska, A.; Szczodrowski, K.; Ryl, J.; Zielińska-Jurek, A.; Siedlecka, E.M. Morphology, Surface properties and photocatalytic activity of the bismuth oxyhalides semiconductors prepared by ionic liquid assisted solvothermal methods. Sep. Purif. Technol. 2019, in press. [Google Scholar] [CrossRef]
  5. Ye, L.Q.; Jin, X.; Liu, C.; Ding, C.; Xie, H.; Chu, K.H.; Wong, P.K. Thickness-ultrathin and bismuth-rich strategies for BiOBr to enhance photoreduction of CO2 into solar fuels. Appl. Catal. B 2016, 187, 281–290. [Google Scholar] [CrossRef]
  6. Jiang, G.H.; Wei, Z.; Chen, H.; Du, X.X.; Li, L.; Liu, Y.K.; Huang, Q.; Chen, W.X. Preparation of novel carbon nanofibers with BiOBr and AgBr decoration for the photocatalytic degradation of rhodamine B. RSC Adv. 2015, 5, 30433–30437. [Google Scholar] [CrossRef]
Figure 1. Photocatalytic activity of prepared photocatalysts toward (a) Rhodamine B, (b) 5-fluorouracil and (c) chromium (VI) under artificial solar irradiation.
Figure 1. Photocatalytic activity of prepared photocatalysts toward (a) Rhodamine B, (b) 5-fluorouracil and (c) chromium (VI) under artificial solar irradiation.
Proceedings 16 00026 g001

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MDPI and ACS Style

Wilczewska, P.; Bielicka-Giełdoń, A.; Borzyszkowska, A.F.; Pieczyńska, A.; Siedlecka, E.M. Influence of Ionic Liquids Assisted Synthesis on Morphology and Photocatalytic Properties of Bi4O5Br2. Proceedings 2019, 16, 26.

AMA Style

Wilczewska P, Bielicka-Giełdoń A, Borzyszkowska AF, Pieczyńska A, Siedlecka EM. Influence of Ionic Liquids Assisted Synthesis on Morphology and Photocatalytic Properties of Bi4O5Br2. Proceedings. 2019; 16(1):26.

Chicago/Turabian Style

Wilczewska, Patrycja, Aleksandra Bielicka-Giełdoń, Agnieszka Fiszka Borzyszkowska, Aleksandra Pieczyńska, and Ewa Maria Siedlecka. 2019. "Influence of Ionic Liquids Assisted Synthesis on Morphology and Photocatalytic Properties of Bi4O5Br2" Proceedings 16, no. 1: 26.

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