Construction And Catalytic Properties Of 0D/2D Controlled Facets Bi~0/Bi₂MoO₆ Schottky Junction Absorbing Materials

At present,the problem of water pollution has aroused constant concern around the world.It is the primary task for researchers to seek a green,economical and efficient water pollution treatment technology.Microwave catalysis has become a new wastewater treatment technology because of its short reaction time and high reaction activity.It is necessary to construct a new catalytic material with high microwave response and catalytic activity.Based on the crystal facets regulation strategy,Schottky junction absorbing material with controllable crystal facets was constructed to improve the carrier separation efficiency and realize the regulation of redox active sites.1.In this paper,Bi~0/Bi₂MoO₆Schottky junction absorbing materials with adjustable 0D/2D crystal facets were constructed by using a simple two-step solvothermal method to grow 0D Bi~0directionally on Bi₂MoO₆nanosheets.XRD,SEM,TEM,XPS,DRS,and DFT were used to characterize the morphology,elemental composition,exposed crystal facets,band gap structure,and charge aggregation properties.The analysis results show that:Bi₂MoO₆has an apparent 2D structure,which supports the growth of Bi~0and further forms a stable and efficient Schottky junction.The Schottky structure formed by Bi~0and Bi₂MoO₆improves the charge transfer efficiency and effectively reduces the recombination of electrons and holes.The unique structure of 0D/2D facilitates multistage reflection and scattering of MW,increasing the surface area and the number of active sites for catalyzed reactions.At the same time,the SPR effect of Bi~0improve the utilization efficiency of MW radiation.It generates a large number of"thermal electrons,"which enables more active substances to participate in the catalytic process and makes the catalytic reaction more efficient.XRD and TEM showed that the exposure ratio of{001}and{010}of Bi₂MoO₆was successfully regulated by changing the p H of the reaction system.2.The constructed Bi~0/Bi₂MoO₆Schottky junction microwave response catalytic material was used for oxytetracycline（OTC）oxidation,Cr（VI）reduction,and perfluorooctanoic acid（PFOA）degradation removal experiments.（1）OTC catalytic oxidation degradation experiments show that the oxidation activity of Bi₂MoO₆{010}was better than that of Bi₂MoO₆{001}.Compared with Bi₂MoO₆{010},15%Bi~0/Bi₂MoO₆{010}composite materials showed the best catalytic effect in the composite with different Bi~0loading ratio and different exposed crystal facets.The degradation rate of OTC reached 93.4%with the amount of catalyst 10 mg and a reaction time of 5 min.The capture experiment showed that h⁺and.O^2-were the main active substances involved in the degradation process.This was due to the high exposure of{010}crystal facets,which resulted in a significant enhancement of oxidation capacity and a large surface area conducive to MW radiation.The directional deposition of Bi~0perpendicular to{010}crystal facets effectively inhibited the recombination of h⁺and e^-,and the OTC catalytic oxidation rate was improved.（2）The reduction experiment of Cr（VI）shows that the reduction activity of Bi₂MoO₆{001}is better than that of Bi₂MoO₆{010}.Compared with Bi₂MoO₆{001},15%Bi~0/Bi₂MoO₆{001}showed the best catalytic effect in the composite with different Bi~0loading ratio and different exposed crystal facets.The reduction rate of Cr（VI）reached 95.9%at the dosage of 50 mg and reaction time of 10 min.The capture experiments show that e^-and.O^2-are the main active substances involved in Cr（VI）reduction,which is due to the directional growth of Bi~0on the highly exposed{001}crystal facet.As an electronic memory,Bi~0continuously receives e^-from Bi₂MoO₆,which effectively inhibits the recombination of h⁺and e^-and stimulates the SPR effect under MW radiation,thus promoting Cr（VI）reduction.（3）Either oxidation path or reduction path can degrade the defluorination of PFOA.The results show that the{010}facet of Bi₂MoO₆is favorable for oxidative defluorination and the{001}facet is favorable for reducing defluorination.15%Bi~0/Bi₂MoO₆{010}showed the best catalytic effect.When the catalyst dosage was 20mg,and the solution p H was 2,the degradation rate of PFOA reached 91.9%and the defluorination rate was 68.1%within 5min.Under the same conditions,the degradation rate of PFOA by 15%Bi~0/Bi₂MoO₆{001}was 74.1%,and the defluorination rate was 52.9%.The central intermediates in the degradation process of PFOA were analyzed by mass spectrometry.The capture experiment showed that e^-was the primary active substance in the reduction defluorination process,and h⁺was the primary active substance in the degradation process,indicating that the redox ability of catalytic materials was significantly different with different exposure facets.