The Study Of Photocatalytic Degradation Of Dyes Based On The Facet Control And Cocatalyst Modified Silver Phosphate

In recent years,with the rapid development of printing and dyeing,the pollution of dye organics in the water environment has become increasingly serious.Due to the high concentration of organic dye wastewater and the difficulty of biochemical degradation,the traditional wastewater treatment technology is difficult to deal with dyeing wastewater.Photocatalytic oxidation,as a new advanced oxidation technology,can realize the efficient degradation of dye organics.Among them,silver phosphate,as a green and efficient photocatalyst,has been widely studied in the field of environment Although silver phosphate has excellent photocatalytic oxidation ability,its photocatalytic performance is limited by the exposure of high-energy crystal surface and the occurrence of photo corrosion:on the one hand,high-energy crystal surface with high catalytic activity is not easy to form in the process of crystal formation;on the other hand,silver phosphate is prone to self-photocorrosion and rapid deactivation in the catalytic process.In order to solve the above two problems,a new silver phosphate based composite catalyst was prepared by ways of crystal surface control and cocatalyst modification,and its degradation behavior and mechanism of dye pollutants were studied.The main work and results are as follows(1)A series of Ag3PO4 polyhedral crystals with the same size but different morphology were prepared by adjusting the amount of key components in the precursor through a facile and controllable method.Three different crystal facets({100},{110}and {111})were completely exposed.It is found that the morphology of Ag3PO4 and its exposed facets are closely related to the content of SDS in the precursor:as a surfactant,SDS can selectively adsorb on the specific crystal surface of silver phosphate,so that there are differences in growth rates among different crystal surfaces,and finally grow silver phosphate crystal exposed specific facets.With the increasing of nSDS/n[Ag(NH3)2]+,the morphology of silver phosphate evolved from cube to dodecahedron and then to tetrahedron,and finally three kinds of silver phosphate single crystals with different crystal faces({100},{110} and {111})were obtained.Compared with cube {100} and tetrahedron {111},dodecahedron {110} silver phosphate shows excellent light response performance,better light absorption capacity and smaller band gap width.With methyl orange and rhodamine as the target pollutants,the {110} crystal surface showed the best photocatalytic degradation efficiency and resistance to light corrosion,which was mainly due to the fact that the specific atoms exposed on the crystal surface not only improved the light absorption ability,but also had higher chemical reaction activity(2)In order to further improve the photocatalytic activity and stability of silver phosphate,a new photocatalytic composite,Pt nanowires anchored dodecahedral Ag3PO4 {110},was prepared by chemical precipitation and hydrothermal reaction Then,the photoelectrochemical properties of the composite were tested.The results show that the composite has higher photogenerated charge separation and transmission efficiency,and longer carrier life,which is due to the high efficiency of Pt nanowires in capturing,conducting and dispersing electrons.In a series of photocatalysts,the composite with shows the highest photocatalytic activity when the content of Pt nanowires is 0.5 ?t%,,and can completely remove rhodamine within 10 minutes.The rate constant is 0.372 min-1?In addition,the material has excellent anti-corrosion performance:even after 10 cycles of degradation experiments,it can still maintain high photocatalytic activity.The free radical capture experiment and EPR analysis show that the hole is the main active species of the composite catalyst for photodegradation of organics,and the ·O2-free radical also plays a certain role in oxidation.The O2 photoelectrochemical reduction curve and UPS spectrum of oxygen show that platinum nanowires can activate the photogenerated electrons produced by silver phosphate,make more effective utilization of photogenerated electrons to reduce oxygen in water,and finally realize the simultaneous enhancement of photocatalytic activity and anti-corrosionIn a word,this work firstly explored the influence of different crystal faces of silver phosphate on its photocatalytic performance,and then,on this basis,a new and efficient visible light recombination photocatalyst was constructed,which enhanced the spatial separation of photocharge and the utilization of photogenerated electrons,and finally achieved excellent photocatalytic activity and stability enhancement of Ag3PO4 based catalysts.