The Controllable Construction Of BiOBr Composites And Their Photocatalytic Applications

Photocatalytic contaminant degradation technology driven by solar light can generate reactive radicals to participate in redox reactions and then mineralize organic macromolecules into inorganic molecules to repair the environment.This process is effective and without secondary pollution,low cost and easy in after-treatment.However,the traditional photocatalysts TiO₂ can only be exited by UV light and miss all the visible light.It can add the cost and operational difficulty of the industrial application,which limit the photocatalytic industrial applications.Therefore,it is vital to develop new semiconductor photocatalysts with wide spectrum response,good stability,efficiency and excellent light energy conversion.BiOBr semiconductor photocatalyst can respond to the visible light and is easy to prepare with stable structure and property.The special layer structures in the crystals cause a good mobility of photogenerated charge carriers and BiOBr thus become a hot spot in this field.However,similar to most photocatalysts,BiOBr has a low utilization to visible light and the photogenerated e^--h⁺pairs are easily recombined,which leads to a poor photoactivity.This paper has combained BiOBr with ferrite nanoparticles and conductive polymer,respectively,to enhance the interface-catalysis performance and the charge carriers'maigration pathes of BiOBr,thus optimize the photodegradation pathway of BiOBr and achieve the aim of photocatalytic enhancement.The main researches are listed as follows:1.Constructing a solid-liquid-interface in situ Fenton-like system to enhance the photoactivity of BiOBr semiconductor.By adjusting the solution pH?pH=1,3 and 7?during the synthesis process of BiOBr to obtain Co_xFe_yO₄-BiOBr composites with three different etched extents.It is discovered that Co_xFe_yO₄ nanoparticles own a high photo-Fenton catalytic property,which can efficiently accelerate the activation of H₂O₂ that in situ generated by BiOBr and more ROSs are produced to enhance the photoactivity of the composites.Bisphenol A?BPA?has been chosen as the target contaminant and the optimized composites were obtained at pH=3,the possible photocatalytic mechanism has been explored preliminarily.2.Preparing the Ni_xFe_yO₄ nanoparticles with different Ni/Fe molar ratio by adjusting the solution pH in the synthesis process and NiFe₂O₄ as the precursor to obtain the Ni_xFe_yO₄-BiOBr composites and the photocatalytic performances have been studied.The results imply that Ni_xFe_yO₄ nanoparticles on the surface of Ni_xFe_yO₄-BiOBr composites can accelerate the activation of H₂O₂ produced by BiOBr to get more ROSs as well,which enhance the photoactivity of composites.The BPA photodegradation mechanism has been further explored and the universality of constructing the solid-liquid-interface in situ Fenton-like process has been verified.3.Given the wide spectrum response and electrical conductivity of conductive polythiophene?PTh?,the PTh-BiOBr photocatalysts have been prepared to build an effective electrons transfer interface between BiOBr and conductive polymers.It is been discovered that?-?^*conjugation effect existed in PTh can broaden the responded visible light spectrum and improve the separation efficiency of e^--h⁺.The generation ability of the active species has been enhanced and compared with BiOBr photocatalysts,about 34%enhancement has been achieved by the optimized composites for BPA photodegradation under visible light.This work prepared a series of green and effective photocatalysts,provided a simpler method for environment repair and simultaneously offered a new thought for photocatalysts modification.