Preparation Of Ultrathin Bi₂O₂?OH?_xCl_2-x Nanosheets And Ultrathin Bi₄O₅Br₂/g-C₃N₄ Composite Photocatalyst And Their Photocatalytic Properties

In recent years,photocatalytic technology has become more and more widely used in the field of wastewater treatment.However,traditional photocatalytic materials have become the bottleneck of their development because of their narrow spectral response and low quantum efficiency.Ultrathin two-dimensional lanthanide semiconductor materials have bright application prospects due to their special micro-morphology and energy level structure.In view of this,the photocatalytic performance and reaction mechanism of the ultra-thin Bi₂O₂?OH?_xCl_2-x and ultra-thin Bi₄O₅Br₂/g-C₃N₄composite photocatalytic materials were studied.The main contents of this study are as follows:?1?Ultrathin Bi₂O₂?OH?_xCl_2-x?0?x?1?nanosheets were prepared by a simple and easy hydrothermal method.The phase composition,morphology and energy level structure of the samples were investigated by various characterization methods.The analysis results show that the use of ethylene glycol and water as the solvent for the hydrothermal reaction is the key factor for the oxygen vacancy?V_o?in the Bi₂O₂?OH?_xCl_2-x sample.At the same time,adjusting the pH value during the hydrothermal process can control the content of OH^-in the Bi₂O₂?OH?_xCl_2-x crystal lattice and control the thickness of Bi₂O₂?OH?_xCl_2-x nanosheets.The energy level structure analysis results show that the introduction of OH^-and V_o in the Bi₂O₂?OH?_xCl_2-x lattice will make its response to the visible spectrum larger.?2?The visible light catalytic performance of different Bi₂O₂?OH?_xCl_2-x samples was studied with ciprofloxacin?CIP?solution as the target pollutant.The experimental results show that the Bi₂O₂?OH?_xCl_2-x-V_o-8 sample has the best visible light catalytic performance.In addition,the photocatalytic mechanism of Bi₂O₂?OH?_xCl_2-x samples was also discussed in this study.The results showed that the hole and superoxide radical?·O₂^-?play a key role in the photocatalytic degradation of CIP effect.The introduction of OH^-in the Bi₂O₂?OH?_xCl_2-x lattice makes it more excellent in the ability to separate photogenerated carriers.At the same time,a large amount of V_o on the{001}crystal plane improved its adsorption capacity for O₂.It promotes the production of O₂^-,which effectively enhances its photocatalytic performance.?3?g-C₃N₄ was prepared by solid-phase method,and g-C₃N₄ was further added during the hydrothermal synthesis of Bi₄O₅Br₂.Ultrathin Bi₄O₅Br₂/g-C₃N₄ composite was successfully synthesized.A variety of characterization methods were used to study the phase composition,morphology and energy level structure of the composite samples.The analysis results show that the special two-dimensional morphology of ultra-thin Bi₄O₅Br₂ and g-C₃N₄ makes it possible to form stable and strong heterogeneous structure,and the composite sample has a wider range of response to the visible spectrum.?4?The photocatalytic activity of the ultrathin Bi₄O₅Br₂/g-C₃N₄ composite was studied with RhB solution as target contaminant.The experimental results show that the Bi₄O₅Br₂-10wt.%C₃N₄ sample has better visible light catalysis active.In addition,the photocatalytic mechanism of the ultrathin Bi₄O₅Br₂/g-C₃N₄ composite photocatalysts was preliminarily discussed.The heterostructure between Bi₄O₅Br₂ and g-C₃N₄ facilitates the separation of photogenerated electrons and holes.The ultrathin Bi₄O₅Br₂/g-C₃N₄ composite sample has better visible light catalytic activity than the single Bi₄O₅Br₂ and g-C₃N₄ samples.The research ultrathin Bi₂O₂?OH?_xCl_2-x and ultrathin Bi₄O₅Br₂/g-C₃N₄ composite photocatalytic materials provides a new idea for the synthesis of ultrathin two-dimensional Bi-based semiconductor materials and their application in the environmental field.