The Study Of The Preparation And Photocatalytic Performance For Ag₃PO₄ And Its Complex Photocatalyst

As we all know,the development of industry is accompanied by low quality of air,serious water pollution and a series of acute energy shortages.Semiconductor photocatalyst as a green environment-friendly purification technology can degrade pollutants purify the environment can also photodissociate water to produce hydrogen and CO₂ and so on to reduce to petroleum and so on.Of all the semiconductor photocatalysts,Ag-based materials have recently been developed into more efficient photocatalysts.Especially,Ag₃PO₄ has been regarded as an attractive material in the field of photocatalysis research,and synergistic action between large dispersion of conduction band?CB?and inductive effect of PO₄^3-was highly beneficial to separation of electron-hole pairs,leading to high oxidative capacities not only for organic dye decomposition but O₂ evolution from water.However,serious photo-corrosion phenomenon for Ag₃PO₄ could easily happen if there was no sacrificial agent or effective transform path to capture photo-generated electrons in the process of photo-catalysis,greatly limiting its practical application.Actually,such photo-corrosion behavior was attributable to more positive conduction band potential?+0.45 eV?and dissociation of Ag⁺from the lattice caused by high solubility of Ag₃PO₄?0.02 g/L?.Therefore,it is high time to work out this issue to make Ag₃PO₄ photocatalyst with higher stability and activity.In order to improve the photocatalytic activity and stability,Ag₃PO₄ based composite photocatalysts were prepared and characterized by XRD,FT-IR,SEM,TEM,DRS,PL,EIS.The photocatalytic properties of Ag₃PO₄and Ag₃PO₄/MOF with different morphologies,the photocatalytic properties and stability of Ag₃PO₄/AgBr were examined.Through combining the results of experiments and calculations,the photocatalytic mechanism of Ag₃PO₄/AgBr was investigated.In this paper,the research contents of Ag₃PO₄ based composite photocatalysts are as follows:?1?Ag₃PO₄ with high active surface{111}exposed surface of Ag₃PO₄ and tetrahedron morphology was prepared by simple liquid phase chemical method.Compared with Ag₃PO₄ crystal synthesized by different preparation methods,this material has superior photocatalytic activity.?2?Ag-MOFs was obtained by reflux reaction and Ag₃PO₄ with{111}exposed surface was loaded on Ag-MOFs by an in-situ fabrication method.There was almost no visible light absorption in the visible region of pure Ag-MOFs.We found that all the samples have good light absorption in the visible region when Ag₃PO₄ was decorated on Ag-MOFs.At the same time,through the photocatalytic experiments,we found that the best catalytic performance was obtained when the Ag₃PO₄:MOF ratio was 2:1 and the degradation rate of methylene blue was reached 96%.?3?AgBr nanoparticles was deposited on Ag₃PO₄ tetrahedron with{111}exposed face by an in-situ ion-exchange method in alkaline environment and constructed Ag₃PO₄@AgBr Z-Scheme structure with intimate contact interface.In this special structure,electrons in the CB of Ag₃PO₄recombined with the photo-induced holes in the VB of AgBr,prospectively suppressing the photocorrosion of the Ag₃PO₄ as well as maintaining excellent photocatalytic activities of Ag₃PO₄@AgBr composite towards the degradation of MB under visible light irradiation.Subsequently,further experimental design was conducted to explain why the photocatalytic efficiency has been improved,and changing of the band gaps was analyzed by theoretical calculations.The effect of different Br^-/PO₄^3-on photocatalytic degradation rate was studied and the results showed that Ag₃PO₄@AgBr with Br^-/PO₄^3-molar ratio was 2:1 showed higher photocatalytic degradation activity?99.8%?than other composites.The rate constant k is 0.285 min^-1.The capture experiment shows that the h+plays more important role than·OH,e^-and·O^2-.The Z-Scheme system of Ag₃PO₄@AgBr and sufficient intimate interface contact between Ag₃PO₄ and AgBr are conducive to the transfer of the carrier and prolong the service life of the carrier.