The Preparation And Synergistic Photocatalytic Performances Of Long Aftergrow Phosphor Couple With Plasmonic Composite Photocatalyst

The photocatalysis requires a continuous photo-assisted,when the light source is turned off,the reaction will stop immediately,which greatly limits its wide applicationst.Long persistence materials because of its nature of the energy storage and release can be used as a support material of round-the-clock semiconductor photocatalytic system.There have been more and more semiconductor photocatalysts assisted by long afterglow materials.Owing to noble metal nanoparticle plasma resonance effect,semiconductor photocatalysts enhances visible light absorption and long afterglow luminescent materials can provide a light source to continuously excite the plasma photocatalyst,allowing it to continue the photocatalytic reaction in the absence of light.In this thesis,the semiconductor photocatalyst is modified by loading noble metal gold nanoparticles to broaden the absorption range of visible light;On the other hand,the synergistic effect of Nano Au’s plasma resonance effect long-lasting phosphor,and the photocatalytic performance toward degrading organic pollutants of long-lasting phosphor-assisted plasma semiconductor photocatalysts in the dark was investigated.（1）SrAl₂O₄:Eu²⁺,Dy³⁺/Au@BiVO₄long-lasting phosphor-assisted plasma semiconductor photocatalysts:Nano Au solution was prepared by a citric acid reduction method,and Au@BiVO₄ plasma photocatalyst was prepared by a sol-gel method.The SrAl₂O₄:Eu²⁺,Dy³⁺/Au@BiVO₄ composite was prepared by assembling a Au@BiVO₄ plasmonic photocatalyst composite with a SrAl₂O₄:Eu²⁺,Dy³⁺long-afterglow phosphor through a sol-gel method followed by a mechanical grinding and calcined under the protection of argon at 400°C for 4 h.XRD,FE-SEM,UV-vis DRS,fluorescence spectrum,XPS,photocurrent density and other characterization methods were used to investigate the crystallinity,surface morphology,light absorption,fluorescence properties,and photoelectrochemical properties of the prepared materials.The experimental results show that the monoclinic Bi VO₄ samples can be obtained by sintering at 500 ^oC for 4 h.The visible light absorption peak and photocurrent response firstly increases and then decreases with the increasing loading amount of Au nanoparticles,and 80%of MB was degraded under visible light within 1h.The organic pollutant MB is degraded useing SrAl₂O₄:Eu²⁺,Dy³⁺/Au@Bi VO₄composite alternately under the conditions of 10 min photodegradation and 90 min darkness degradation.The degradation efficiency toward MB is improved both with visible light irradiation and keep in darkness.The degradation efficiency toward MB can be up to 7%in darkness.The results show that the light energy emitted by the long afterglow materials can be absorbed by Bi VO₄ efficently and the plasmon resonance effect of nano-gold improves the response range of Bi VO₄ to long afterglow materials.The main active materials for degradation are hydroxyl radicals and holes.（2）SrAl₂O₄:Eu²⁺,Dy³⁺/Au@SrTiO₃long-lasting phosphor-assisted plasma semiconductor photocatalysts:SrTiO₃with cubic perovskite structure was prepared by a solvothermal method,and Au@SrTiO₃sample was synthesized by a citric acid reduction method.The SrAl₂O₄:Eu²⁺,Dy³⁺/Au@SrTiO₃ composite was prepared by assembling a Au@SrTiO₃ plasmonic photocatalyst composite with a SrAl₂O₄:Eu²⁺,Dy³⁺long-afterglow phosphor through citric acid reduction method method followed by a mechanical grinding and calcined under the protection of argon at 300°C for 4 h.XRD,FE-SEM,UV-vis DRS,fluorescence spectrum,XPS,photocurrent density and other characterization methods were used to investigate the crystallinity,surface morphology,light absorption,fluorescence properties,and photoelectrochemical properties of the materials.The experimental results show that with the nano-gold loading,Au@SrTiO₃ has a strong absorption band in the visible light region due to the nano-gold plasmon resonance effect.When the loading of nano-gold reaches 1.42 wt%,the absorption intensity of the diffuse reflection spectrum of Au@SrTiO₃ is the largest and overlaps with the emission peaks of SrAl₂O₄:Eu²⁺,Dy³⁺maximally,and the photocurrent response intensity also reaches the maximum.Degradation experiments show that pure SrTiO₃ sample cannot take advantage of the afterglow emitted by long afterglow luminescent materials in dark and has no activity in dark.When long aftergrow phosphor is coupled with Au@SrTiO₃ sample,the efficiency of photocatalytic degradation of Rh B is improved in both visible light and in dark.After Alternating degradation experiment in lighting for 15 min and darkness for 120 min,degradable 6%Rh B in darkness.The main active ions for degradation are mainly holes.（3）SrAl₂O₄:Eu²⁺,Dy³⁺/Au@ZnO long-lasting phosphor-assisted plasma semiconductor photocatalysts:Nano Au solution was prepared by a citric acid reduction method,and Au@ZnO plasma photocatalyst was prepared by a sol-gel method.The SrAl₂O₄:Eu²⁺,Dy³⁺/Au@ZnO composite was prepared by assembling a Au@Zn O plasmonic photocatalyst composite with a SrAl₂O₄:Eu²⁺,Dy³⁺long-afterglow phosphor through a sol-gel method followed by a mechanical grinding and calcined under the protection of argon at 400°C for 4 h.XRD,FE-SEM,UV-vis DRS,fluorescence spectrum,XPS,photocurrent density and other characterization methods were used to study the crystallinity,surface morphology,light absorption,fluorescence properties,and photoelectrochemical properties of the materials.The experimental results show that the wurtzite-type Zn O was prepared at 600°C for 2 h.When the loading of nano-gold reaches 1 wt%,the absorption intensity of the diffuse reflection spectrum of Au@Zn O is the largest and overlaps with the emission peaks of SrAl₂O₄:Eu²⁺,Dy³⁺maximally,and the photocurrent response intensity also reaches the maximum.Degradation experiments show that pure Zn O sample cannot take advantage of the afterglow emitted by long afterglow luminescent materials in darkness and has no activity in dark.When long aftergrow phosphor is coupled with Au@Zn O sample,the efficiency of photocatalytic degradation toward RhB is improved both with visible light irradiation and keep in darkness.After Alternating degradation experiment in lighting for 10 min and darkness for 120 min,the degradation efficiency toward Rh B can be up to 7%in darkness.The main degradation active ions are alternately acted by holes,hydroxyl radicals and superoxide radicals.