Preparation And Photocatalytic Performance Of Bi₂MoO₆-based Binary/three-way Photocatalysts

As one of the advanced oxidation technologies,photocatalytic technology can use clean and renewable solar energy,to deal with increasingly serious global environmental problems,with potential application prospects.In recent years,Bi₂MoO₆?BMO?has visible light responsiveness due to its relatively narrow band gap energy?2.6².8 eV?,which has become a research hotspot of new visible light photocatalysts.However,pure BMO crystals have defects in that photogenerated electron holes are easy to recombine and have low quantum efficiency.This has greatly limited its application in wastewater treatment.In view of the above problems,the use of composite modification to obtain binary or ternary BMO composites is an effective means.In order to improve the photocatalytic activity of BMO,a binary CeO₂/BMO heterojunction was formed by BMO and CeO₂,and carbon nucleus?CDs?and carbon nanofibers?GNFs?were modified together to obtain CDs/BMO/GNFs ternary composites.The RGO/Ag/BMO ternary composites were prepared by composite of reduced graphene oxide?RGO?and Ag.The photocatalytic activity of the above binary and ternary composites was further studied.The law of influence.The specific research contents are as follows:?1?Different proportions of CeO₂/BMO nanocomposites were synthesized.The effects of pH?2⁹?and Ce/Bi molar ratio?3%¹0%?on photocatalytic properties were investigated.The results showed that when pH=6,the photocatalytic activity of BMO was the strongest,pH=6,and the content of CeO₂ was 5%.The prepared sample5%CeO₂/BMO showed the highest photocatalytic activity.The rate constants for photocatalytic degradation of Rhodamine B?RhB?,methylene blue?MB?and phenol were 0.037,0.016 and 0.007 min^-1,respectively,which were 3.19,1.70 and 4.58 times higher than pure BMO,respectively.The mechanism of photocatalytic performance enhancement is mainly composed of CeO₂ and Bi₂MoO₆ to form a heterojunction,which is beneficial to the effective separation of photogenerated electron-holes,thereby increasing the content of active free radicals involved in the reaction.?2?The new ternary CDs/BMO/GNFs composites were synthesized by hydrothermal method,and their morphology,structure,physicochemical properties and photocatalytic activity were studied.The results show that the loading of CDs and GNFs has significant photocatalytic properties.Impact.When the molar ratio of Bi/C is 0.2 and the amount of CDs added is 5 mL,the prepared ternary composite C5/BMO/GNF-0.2 has the best photocatalytic activity for RhB,that is,after 45 min of illumination to RhB.The removal rate can be as high as 99.4%.The reason is mainly due to the synergy between the ternary components?CDs,BMO and GNFs?,which facilitates the efficient separation of photogenerated electrons and holes.Free radical trapping experiments and electron spin resonance experiments confirmed that holes,·O₂^-and·OH active free radicals are involved in the photocatalytic degradation process.?3?The Bi₂MoO₆/RGO?BMG-X?binary composites were prepared first,and the effects of different mass ratios?0,0.25,2,4,5 wt%RGO?on their photocatalytic properties were investigated.The binary composite?BMG-2?prepared by wt%RGO composite has the best photocatalytic activity.A certain amount of Ag was modified on the surface to obtain Ag/BMO/RGO-2?Ag/BMG-2?ternary composite.The characterization results show that under the action of RGO and Ag,the specific surface area of BMG-2 is increased,the structure of the material is improved,and its absorption in the visible region is facilitated.And the photocatalytic activity of Ag/BMG-2 was significantly enhanced.The rate constants of photocatalytic reaction of RhB,methylene orange?MO?and phenol were 0.0405,0.0257 and 0.0153 min^-1,respectively,which were improved compared with pure BMO.23.8,16.1 and 9.56times.Cyclic experiments show that the Ag/BMG-2 ternary composite has good chemical stability.