Application Of Novel Ag₃PO₄/MWCNTs/Bi₂WO₆ Photocatalyst For Removal Of Antibiotic In Water

Bismuth tungstate（Bi₂WO₆）,as a widely used photocatalytic material,has the advantages of narrow band gap,easy to drive by visible light,strong oxidation ability,efficient degradation of organic pollutants,high photochemical stability and low cost.In order to further improve its photocatalytic performance,Bi₂WO₆is always combined with other semiconductor materials to form heterojunction photocatalysts,which can effectively reduce the recombination efficiency of photogenerated charge carriers and enhance the utilization of solar energy.Ag₃PO₄/MWCNTs/Bi₂WO₆ with different mass ratios were prepared by a simple hydrothermal and deposition procedure.The results of scanning electron microscopy（SEM）,transmission electron microscope（TEM）and X-ray photoelectron spectroscopy（XRD）showed that Ag₃PO₄/MWCNTs/Bi₂WO₆ ternary heterojunctions were successfully synthesized.Ag₃PO₄/MWCNTs/Bi₂WO₆ heterojunctions shows excellent photocatalytic performance for removal of tetracycline（TC）.Of which,the photocatalytic performance of 15%Ag₃PO₄/MWCNTs/Bi₂WO₆ is best,and the removal rate of TC can reach 82%under visible light irradiation for 1 h.And its catalytic activity is higher than that of pure materials（Ag₃PO₄、Bi₂WO₆）and related binary composites（MWCNTs/Bi₂WO₆ and Ag₃PO₄/Bi₂WO₆）.The results of UV-vis diffuse reflection spectrum（UV-vis DRS）indicated that the addition of Ag₃PO₄ and MWCNTs increased the response range of Bi₂WO₆ to visible light.And the results of photoluminescence spectra（PL）and photoelectrochemical experiment confirmed that the composition of ternary heterojunction greatly reduces the recombination efficiency of photogenerated charge carriers.The hole（h⁺）and superoxide radical（·O₂^-）radicals were confirmed that played a key role in the photodegradation system by free radical quenching experiment and electron spin resonance（ESR）.This paper proposes that Ag₃PO₄/MWCNTs/Bi₂WO₆ photocatalyst has multiple charge-carrier transfer channels in the process of photocatalytic degradation of TC:（i）Z-scheme charge transfer channel was formed by Ag₃PO₄,Bi₂WO₆ and Ag NPs;（ii）Ag NPs showed surface plasmon resonance（SPR）effect;（iii）Ag NPs and multi-walled carbon nanotube（MWCNTs）showed the"electron sink"property.Ag₃PO₄/MWCNTs/Bi₂WO₆ possessed good photochemical stability in cyclic experiments.Finally,the photocatalytic degradation of other antibiotics by Ag₃PO₄/MWCNTs/Bi₂WO₆ was also studied and the application prospect of Ag₃PO₄/MWCNTs/Bi₂WO₆ in wastewater treatment was simulated.This study proves that photocatalytic performance can be effective improved by constructing a multiple charge-carrier transfer system,which provides a reference for the construction of photocatalytic composite materials with multiple charge-carrier transfer system.