Preparation And Characterization Of Bismuth Bromide Oxide-based Composite Photocatalytic Materials

Energy shortage and environmental pollution problems have become global issues that need to be resolved in the 21st century.Semiconductor photocatalysis technology is expected to become one of the best solutions to the above problems.Traditional semiconductor photocatalysis,such as TiO₂,can only use a small part of solar energy.Therefore,the problem of seeking visible light driving and reducing the carrier recombination rate of single-phase semiconductors has quickly become a research hotspot.Due to its unique layered structure,BiOBr can connect the[Bi₂O₂]layer and the Br atomic layer within the molecule with van der Waals force to form a built-in electric field,which promotes the photocatalytic activity of the semiconductor.In addition,the pH value can be adjusted during the hydrothermal synthesis of BiOBr so that it undergoes debromination reaction to produce Bi₃O₄Br.Due to the lack of a part of Br atoms in the molecular structure of Bi₃O₄Br and the change of the environment of Bi connection,it has a more negative conduction band position,which in turn The band gap is reduced and the optical absorption response range is increased,so both are of great research significance.In this paper,the CQDs/Bi₃O₄Br composite system was successfully synthesized by hydrothermal method for the first time,and the phase structure of the synthesized sample was characterized by XRD.In the FTIR test,the tensile vibration of the C-O group at 1386cm-1 was found in the CQDs/Bi₃O₄Br system.The single-phase Bi₃O₄Br in the control group does not have this perturbation,so it proves the successful synthesis of the CQDs/Bi₃O₄Br composite phase,and then the CQDs are observed to be distributed on the flake Bi₃O₄Br in TEM pictures.PL tested that the CQDs/Bi₃O₄Br composite phase samples have lower carrier recombination efficiency;the carrier lifetime of the 0.25-B composite phase samples is 0.5103ns longer than the single-phase Bi₃O₄Br 0.3278ns;the absolute quantum production of the 0.25-B samples The rate is 4.14%is also higher than the single-phase Bi₃O₄Br 3.21%;compared with single-phase Bi₃O₄Br,0.25-B also has a larger photo-generated current;these optical tests show that CQDs/Bi₃O₄Br has lower photo-generated carrier recombination efficiency.The CQDs/Bi₃O₄Br system has better photocatalytic degradation activity for RhB,TC and BPA,and the sample has better stability.The experiment of the capture agent shows that the active materials of the CQDs/Bi₃O₄Br system during the photocatalytic degradation process are holes and super Oxygen free radicals,and a possible photocatalytic degradation mechanism is proposed accordingly.In this paper,Bi₄O₇ was synthesized by low-temperature hydrothermal synthesis of KBiO₃ prepared by oil bath method,and then the compound photocatalyst of Bi₄O₇/BiOBr was synthesized by in-situ ion etching for the first time.The phase structure of Bi₄O₇/BiOBr system was characterized by XRD;the microscopic morphology of the sample was observed by SEM image.The DRS test shows that the Bi₄O₇/BiOBr composite phase has a wider optical response.The PL shows that the composite phase has a lower carrier recombination efficiency,and the Bi₄O₇/BiOBr system has better visible light degradation RhB activity.The experimental results of the capture agent in the Bi₄O₇/BiOBr system show that the active substances in the photocatalytic degradation process of the system are superoxide radicals and holes.Finally,a possible photocatalytic degradation mechanism of the Bi₄O₇/BiOBr system is proposed.