Heterojunction Interface Design,Preparation And Photocatalytic Properties Of Bismuth Halide Based Composites

In recent decades,a large amount of research has been conducted on the sustainable development of green methods to to deal with natural environmental pollution issues.As solar energy is an inexhaustible source of green energy,photocatalysis is considered to be one of the most promising methods for environmental remediation.In photocatalytic reactions,pollutants such as organic molecules,toxic gases,and heavy metal ions can be efficiently degraded,mineralized,or reduced to harmless inorganic substances.Based on this,this article used bismuth oxyhalides（BiOX,X=Cl,Br,I）as the base material and successfully prepared BiOX-based photocatalytic composite materials with excellent light response performance through methods such as morphology control and heterostructure construction.By analyzing the microstructure,phase structure,and photocatalytic performance,the relationships between the structure and performance of BiOX-based photocatalytic composite materials were established,and its photocatalytic mechanism is elaborated.The main research content are:（1）PDA@CdS composites were prepared via in-situ growth method,and CP60 was the best-performing material after encapsulation upon CdS.CdS@PDA/BiOBr Z-scheme heterojunction composites were prepared using CP60,and CdS@PDA/BiOBr effectively degraded Rhodamine B（Rh B）under visible light.The microstructure and morphology was explored using X-ray diffractometer（XRD）and scanning electron microscope（SEM）.The composition and chemical states of materials were analyzed using X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectra（FTIR）.Photoluminescence Spectroscopy（PL）,electrochemical tests,UV-vis absorption spectra（UV-vis）and trapping experiments were used to analyze the photocatalytic mechanism.The Mott-Schottky curves of the material and energy band analysis from UV-vis diffuse reflectance spectra（UV-Vis DRS）,indicating that the in-built electric field formed between interface,which enhanced the separation and transfer of photo-generated electron-hole pairs to the surface position of the photocatalytic reaction.（2）CdS@PDA/BiOI was prepared by solvent method using CP60,which constructed tightly stacked Z-scheme heterojunction.Compared to BiOI,the optimized CPBI-1.0exhibits the optimal Rh B degradation efficiency（98.8%）.UV-Vis DRS,Electrochemical Impedance Spectroscopy（EIS）and PL confirmed that the formation of Z-scheme heterojunction between CdS@PDA and BiOI accelerating the separation and transfer of carriers.Trapping experiments further confirmed that the dominant active species were Superoxide radical(·O^2-),accounting for the quickly degradation of Rh B.（3）Ti₃C₂/BiOCl_xBr_1-x heterojunction photocatalysts were prepared via solvothermal synthesis method.XRD,SEM,transmission electron scope,and XPS analysis indicates that BiOCl_xBr_1-x is successfully in-situ grown upon Ti₃C₂ nanosheets.Visible light photocatalytic performance of 7%-Ti₃C₂/BiOCl_0.25Br_0.75 is overwhelmingly superior to BiOCl_xBr_1-x with an increment of 11.9 times in the reaction rate constant of Rh B photodegradation,owing to the distinctive Schottky heterojunction between Ti₃C₂ and BiOCl_xBr_1-x.UV-Vis DRS,PL,FTIR,Raman,EIS,and transient photocurrent response account for the improved utilization of visible light,effective separation of photogenerated carriers,and more photogenerated electron acceptors,which elucidate the superior photocatalytic performance and good stability of Ti₃C₂/BiOCl_xBr_1-x.Trapping experiments and electron paramagnetic resonance tests verify that the dominant active species such as·O^2-and hole（h⁺）are responsible for the rapid degradation of Rh B.The reasonable photocatalytic mechanism of Ti₃C₂/BiOCl_xBr_1-xis clarified based on the energy band structure and synergistic effect of the heterojunction.