Study On The Preparation,Modification And Photocatalytic Performance Of Bismuth-contained Coordination Polymers

Photocatalysis is now regarded as a promising and environment-friendly technology which is used to treat printing and dying wastewater widely.Recently,many coordination polymers were applied in the field of photocatalysis because of their merits such as diversity of species,controllability of structure,thermal stability and large surface areas.In addition,bismuth-based oxides became visible-light active photocatalysts with prospective development because of their narrow band gaps.In recent years,graphene,a new material with outstanding conductivity and adsorption properties,is often made into composites with other materials and the composites usually show remarkable photocatalytic performance,which make photocatalysis technology get fast development.Considering bismuth-contained coordination polymers and its photocatalytic activity are rarely reported,the main research contents of this paper are as follows:Firstly,a new kind of bimetal coordination polymer containing cobalt and bismuth?24pCoBi?with two-dimensional structure was synthesized by hydrothermal method.Its chemical fomula is BiCoC₂₁H₁₇N₃O₁₆.24 pCoBi was calcined at high temperature to get a composite?24pCoBi500?.Both of the two materials were characterized by some methods and the band gap approximations were also calculated.The photocatalytic performances of two materials degradating methylene blue?MB?aqueous solution under simulated sunlight are in order: 24pCoBi500>24pCoBi,while 24pCoBi>24pCoBi500 for the two materials degradating rhodamine B?RhB?aqueous solution under visible light.24 pCoBi shows high performance of degradating RhB in strong acid condition and denaturation in strong alkaline condition?pH>12.40?during the experiment of changing the pH of RhB aqueous solution.Secondly,a structure-known bimetal coordination polymer containing copper and bismuth?35pCuBi?was calcined at high temperature to get a composite?35pCuBi500?.A composite of 35 pCuBi and graphene?35pCuBi/Gr?was synthesized by hydrothermal method.All the three materials were characterized by some methods and the band gap approximations were also calculated.The photocatalytic performances of three materials degradating MB aqueous solution under simulated sunlight and RhB aqueous solution under visible light are in order: 35pCuBi500>35pCuBi/Gr>35pCuBi.35 pCuBi shows high performance of degradatingRhB in strong acid condition during the experiment of changing the pH of RhB aqueous solution and the optimum pH is 1.82.Finally,the photocatalytic reaction mechanism of 35pCuBi/Gr is discussed.In the structure of 35pCuBi/Gr,the excellent conductivity of graphene can accelerate electron transfer,reduce electron-hole recombination rate and improve the utilization of sunlight.Its high adsorption ability can make photocatalysts in full contact with organic molecules to accelerate the process of photocatalytic reaction.The experimental results show that35pCuBi/Gr can degrade up to above 97% of RhB aqueous solution under visible light in 10 minutes and its structure was maintained in two cycles of degradation.