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

With the continuous advancement of high-quality economic and social development,environmental pollution problems are increasingly frequent around the world.Among them,environmental sewage containing perfluoroalkyl compounds poses a serious threat to human health.Therefore,finding a green and efficient way to improve environmental pollution to deal with environmental sewage containing perfluoroalkyl compounds has become the primary task of researchers who have been committed to environmental pollution problems.In this paper,based on the adjustment of controllable crystal facet,a Schottky junction absorbing material with"crystal facet heterojunction"was constructed,and an efficient REDOX dual-channel catalytic degradation mode was formed for the purification of environmental wastewater containing perfluoroalkyl compounds.In this paper,the main material of 2D BiOBr layered nanosheets with different exposed crystal facets was prepared by hydrothermal method and p H of reaction system was controlled.In order to further improve the microwave absorption performance,0D Bi~0 was loaded onto 2D BiOBr nanosheets by solvothermal method,and then Bi~0/BiOBr Schottky junction absorbing material with 0D/2D controllable crystal facet was constructed.The apparent morphology,exposed crystal facet,elemental composition,band gap structure and photoelectric properties were investigated by means of SEM,TEM,XRD,XPS,DRS,M-S,EIS and PL.The results show that the exposure ratio of(102)crystal facet and(110)crystal facet in BiOBr is successfully changed by adjusting p H.The 0D Bi~0 was directionally grown on the reduced crystal facet of the 2D BiOBr nanosheet to form a stable Schottky junction.After loading Bi~0,the band gap of BiOBr composite catalyst material is significantly reduced,the optical absorption range is further expanded,and the carrier separation and migration efficiency is significantly improved.Bi~0/BiOBr Schottky junction absorbing material was used for defluorination of perfluorooctanoic acid(PFOA)and perfluorooctane sulfonic acid(PFOS)under microwave radiation.Defluorination of PFOA:Under microwave irradiation,compared with composites with different Bi~0 loads,15%Bi~0/BiOBr-1:1 showed excellent degradation effect on PFOA.When the dosage was 20 mg and the p H value was 4.2,the degradation rate could reach 97.73%and the defluorination rate could reach 70.08%within 5minutes.In addition,it is proved that Bi~0/BiOBr-1:1 has stronger adsorption capacity for PFOA through infrared spectrum experiment.The experimental results showed that the defluorination of PFOA could be carried out through oxidation and reduction paths.The(102)crystal facet of BiOBr tends to degrade by reduction,and the(110)crystal facet tends to degrade by oxidation.The BiOBr-1:1 of both(102)and(110)crystal facets can form"crystal heterojunction"and open a fast catalytic mode of REDOX dual channel.In order to further verify the differences in the REDOX capacity of Bi~0/BiOBr,the REDOX properties of different crystal facets were further compared by the experiments of oxidation OTC and reduction Cr(VI).The mode of charge transfer in Schottky junction was demonstrated by XPS before and after the reaction.Through capture experiments,it is proved that e~-is the main active species leading the reduction degradation of(102)crystal facet,h~+is the main active species leading the oxidation degradation of(110)crystal facet,e~-and h~+can jointly participate in the catalytic reaction of REDOX dual channel.Defluorination of PFOS:Under microwave irradiation,compared with composites with different Bi~0 loads,15%Bi~0/BiOBr-1:1 showed the best catalytic effect.When the dosage was 20 mg and the p H value was 4.2,the degradation rate could reach 96.90%and the defluorination rate could reach 66.26%within 5 minutes.The results show that the defluorination of PFOS can also be carried out through oxidation and reduction paths.Bi~0/BiOBr-1:1 materials can form"crystal heterojunction"inside,opening the rapid degradation of PFOS through REDOX dual channels.Through capture experiments,it is proved that e~-is the main active species leading the reduction degradation of(102)crystal facet,h~+is the main active species leading the oxidation degradation of(110)crystal facet,e~-and h~+can jointly participate in the catalytic reaction of REDOX dual channel.The tunable"crystal facet heterojunction"can effectively adjust the ratio of electron to hole,improve the efficiency of carrier separation and catalytic reaction activity.