Study On The Properties Of Semiconductor Photocatalytic Materials And Their Photocatalytic Degradation Of Organic Pollutants Based On BiVO₄

BiVO₄ is a stable semiconductor material with a band gap of only 2.4 eV,extending the range of light absorption to the visible region.It does not contain toxic elements such as lead,cadmium and mercury,and is a green metal oxide.BiVO₄ has excellent photocatalytic properties,is non-toxic and recyclable,and is widely used in photocatalysis.On the other hand,although BiVO₄ is an excellent photocatalyst,BiVO₄ also has the disadvantage that photogenerated electrons are easily compounded and have a small specific surface area.We need to find ways to further improve its photocatalytic performance and obtain higher activity photocatalysts.In this paper,a variety of modification techniques were used to modify BiVO₄.At the same time,we used a variety of analytical testing methods to systematically study the properties of BiVO₄ photocatalytic composites and the mechanism of photodegradation of antibiotic organic pollutants.The specific research work is as follows:?1?The Fe₂O₃/BiVO₄ heterojunction microcapsule composite photocatalyst was synthesized by hydrothermal method using Fe₂O₃ as template and in situ growth method to crystallize BiVO₄particles on the surface of Fe₂O₃ micron box.The Fe₂O₃/BiVO₄ micron box structure was analyzed according to TEM and other characterization methods.The physicochemical properties of Fe₂O₃/BiVO₄ heterojunction micron box composite photocatalysts were characterized by XRD,TEM,SEM and BET.The results of the photodegradation experiment showed.When the ratio of Fe₂O₃ to BiVO₄ is 3:1,the Fe₂O₃/BiVO₄ heterojunction micron box composite photocatalyst exhibits the best photocatalytic degradation activity for tetracycline?TC?.0.05 g catalyst is 20 mg L^-1 in 2 h.The tetracycline degradation rate of 1 reached 75%.The photodegradation reaction mechanism of photocatalyst was investigated by free radical trapping experiments.Through the cycle experiment,the stability and reusability of the photocatalyst were explored.?2?Using rheological method and three-dimensional graphene?rGH?as load,rGH/BiVO₄three-dimensional graphene-loaded BiVO₄ composite photocatalytic material was synthesized.The rhGH/BiVO₄ three-dimensional graphene-loaded BiVO₄ composite photocatalytic material with different loading ratios was prepared by adjusting the addition amount of three-dimensional graphene.XRD,TEM,SEM,UV-vis and other methods are used to characterize.The photodegradation activity of different ratios of rGH/BiVO₄ three-dimensional graphene-loaded BiVO₄ composite photocatalytic materials was investigated with tetracycline as the target antibiotic.It was found that the photodegradation of the material when the mass fraction of three-dimensional grapheme reached 1%It has the strongest activity and can achieve a degradation rate of 75%to 20mg L^-1 TC at 2 h.?3?Using carbon hydrothermal synthesis method,carbon quantum dots?CQDs?are doped into rGH/BiVO₄ three-dimensional graphene-loaded BiVO₄ composite photocatalytic material,and the volume of carbon quantum dots solution is adjusted to prepare the volume of the drop.BiVO₄-supported three-dimensional graphene composite photocatalysts modified with different quantum ratios of carbon quantum dots.The physicochemical properties of the prepared different volume doped photocatalysts were characterized by various analytical methods such as XRD,TEM and electrochemistry.The photodegradation activity of the material was evaluated by degrading the contaminant with tetracycline solution.It was found that the photocatalytic activity of CQDs/rGH/BiVO₄ composite photocatalyst was the best when the volume of carbon quantum dots was 7 mL.The photocatalyst can degrade the tetracycline of 20 mg L^-1 to 80%within 2 h.