Title:One-post Solvothermal Synthesis of Bismuth Oxybromides for Efficient Visible-light Photocatalytic Degradation of Methyl Parahydroxybenzoate: Effects of Alkaline and Reaction Medium
VOLUME: 1
Author(s):Jiaxiu Xiao, Xiaoting Zhang, Yaoyao Huang, Xiuling Luo and Xin Xiao*
Affiliation:School of Chemistry, South China Normal University, Guangzhou 510006, School of Chemistry, South China Normal University, Guangzhou 510006, School of Chemistry, South China Normal University, Guangzhou 510006, School of Chemistry, South China Normal University, Guangzhou 510006, School of Chemistry, South China Normal University, Guangzhou 510006
Keywords:Photocatalysis, Visible-light, Bismuth oxybromides, Methyl parahydroxybenzoate, Photocatalytic mechanism, Advanced Oxidation Processes (AOP).
Abstract:Background: The development of high-efficiency visible-light-active photocatalysts to eliminate emerging contaminants is of great significance for environmental remediation and personal safety.
Methods: In this work, BiOBr and two oxygen-rich bismuth oxybromide (Bi4O5Br2-EG and Bi4O5Br2-H2O) were synthesized by solvothermal method through the reaction of Bi3+ and Br- in different reaction medium (ethylene glycol or
water) and alkali conditions. The composition, structure, morphology, light absorption, surface area, and surface feature of
the synthetic bismuth oxybromides were systematically characterized. Due to the presence of ethylene glycol and OH-, the
Bi4O5Br2-EG preferentially exposes the {010} facets. The formation of hierarchical flower-like structures of Bi4O5Br2-
EG can be elucidated by the dissolution-recrystallization-growth mechanism. The bismuth oxybromides were then used for
photocatalytic degradation of methyl parahydroxybenzoate (a commonly used preservative but exposes endocrine disrupting
activity) under visible-light irradiation.
Results: Since Bi4O5Br2-EG has a satisfactory band structure (bandgap energy ~2.61 eV, valence band potential +2.45 V),
high surface area (49.0 m2g-1), and negatively charged surface, its photocatalytic removal efficiency of MPHB is 46.5 and
41.2 times that of BiOBr and Bi4O5Br2-H2O, respectively. During the photodegradation reaction, holes and superoxide
radicals were recognized as the key reactive oxide species.
Conclusion: In addition, the as-synthesized Bi4O5Br2-EG is stable and easy to reuse, suggesting it is a potential candidate
for wastewater treatment.
