Preparation Of Cu And Yb Doped TiO₂ Photocatalysts By Microwave Hydrothermal Method And Their Catalytic Activity

In this paper,the copper and ytterbium doped TiO₂ photocatalyst TiO₂-Cu,TiO₂-Yb and TiO₂-Yb-Cu were prepared by microwave hydrothermal synthesis method.The photocatalytic activity for three kinds of catalysts were inverstigated by using methyl orange as model pollutant in the homemade mercury lamp,microwave?MW?,ultraviolet?UV?,microwave and ultraviolet?MW-UV?degradation conditions.The influence of preparation conditions such as doping ratio,reaction time,reaction temperature and microwave power of the microwave hydrothermal parallel synthesis,calcination temperature and calcination time of the muffle furnace on the photocatalytic activity of the catalyst were investigated.The structure of the catalysts was analyzed by IR,XRD,SEM,Raman,AFM and N₂ adsorption desorption test method.The reason for influencing the structure of the catalyst on the photocatalytic activity was discussed by the above characterization means.The main results was as follows:1.Preparation of TiO₂-Cu catalyst by microwave hydrothermal method andits photocatalytic activityThe optimum conditions for the preparation of TiO₂-Cu photocatalyst by microwave hydrothermal method were as follows:Cu doped amount n(Cu²⁺)/n(Ti⁴⁺)=0.08%,reaction temperature 160?,reaction time 3.5 h,microwave power 600 W,calcination temperature 600?and calcination time 3 h.The degradation rate of methyl orange was 96.04%when TiO₂-Cu catalyst was used for the degradation of methyl orange solution for 50 min in the self-made UV lamp.And the degradation rate of methyl orange were respectively 15.98%,98.26%and 100%with MW,UV and MW-UV three kinds of conditions for degradation of methyl orange for 50 min in the synthesis of UV instrument computer combination of microwave ultrasonic catalysis.The methyl orange was completely degraded as the visible light used for degradation of methyl orange solution for 4 h.The results from ICP-AES,XRD,SEM,Raman,AFM,N₂ adsorption desorption,PL and IR analysis showed that the Cu was doped into the TiO₂ catalyst in the process of preparing TiO₂-Cu by the microwave hydrothermal method.And more the copper doped increasing·OH in TiO₂-Cu catalyst,the catalyst surface defects increased,the electron hole increased,thus the TiO₂-Cu catalyst with small particle size,high crystallinity,agglomeration of small and large specific surface area,as a result it had high photocatalytic activity.And more the TiO₂-Cu catalyst had higher photocatalytic activity when the relative mass fraction of rutile phase and anatase phase was between 0.6%⁹.0%and 91.0%⁹9.4%.2.Preparation of TiO₂-Yb catalyst by microwave hydrothermal method andits photocatalytic activityThe optimum conditions of TiO₂-Yb photocatalyst prepared by microwave hydrothermal method were as follows:ytterbium doped amount n(Yb³⁺)/n(Ti⁴⁺)=0.14%,reaction temperature 160?,reaction time 3.5 h,microwave power 600 W,calcination temperature 650?and calcination time 2.5 h.The degradation rate of methyl orange was 98.68%when TiO₂-Yb catalyst was used for the degradation of methyl orange solution for 50 min in the self-made UV lamp.And the degradation rate of methyl orange were respectively 16.21%,98.71%and 100%with MW,UV and MW-UV three kinds of conditions for degradation of methyl orange for 50 min in the synthesis of UV instrument computer combination of microwave ultrasonic catalysis.The methyl orange was completely degraded as the visible light used for degradation of methyl orange solution for 4 h.The results from ICP-AES,XRD,SEM,Raman,N₂ adsorption desorption,PL and IR analysis showed that the Yb was doped into the TiO₂ catalyst in the process of preparing TiO₂-Yb by the microwave hydrothermal method.And more the ytterbium doped increasing·OH in TiO₂-Yb catalyst,the catalyst surface defects increased,the electron hole increased,thus the TiO₂-Yb catalyst with small particle size,high crystallinity,agglomeration of small and large specific surface area,as a result it had high photocatalytic activity.And more the TiO₂-Yb catalyst prepared by microwave hydrothermal method had low fluorescence intensity,which indicated that ytterbium doped could inhibit the recombination of photogenerated electron hole,led to the TiO₂-Yb catalyst had high photocatalytic activity.3.Preparation of TiO₂-Yb-Cu catalyst by microwave hydrothermal methodand its photocatalytic activityThe best conditions for preparation of TiO₂-Yb-Cu photocatalyst by microwave hydrothermal method were as follows:copper and ytterbium doped amount n(Yb³⁺)/n(Ti⁴⁺)=0.16%and n(Cu²⁺)/n(Ti⁴⁺)=0.04%,reaction temperature 120?,reaction time 3 h,microwave power 650 W,calcination temperature of 600?and calcination time of 5.5 h.The degradation rate of methyl orange was 99.06%when TiO₂-Yb-Cu catalyst was used for the degradation of methyl orange solution for 50min in the self-made UV lamp.And the degradation rate of methyl orange were respectively 19.10%,100%and 100%with MW,UV and MW-UV three kinds of conditions for degradation of methyl orange for 50 min in the synthesis of UV instrument computer combination of microwave ultrasonic catalysis.The degradation rate of methyl orange was 98.42%when the visible light was used for the degradation of methyl orange solution for 1.5 h.But the methyl orange was completely degraded as the visible light used for degradation of methyl orange solution for 4 h.The results from ICP-AES,XRD,SEM,Raman,N₂ adsorption desorption,PL and IR analysis showed that the copper and ytterbium doped increasing·OH in the process of preparing TiO₂-Yb-Cu by the microwave hydrothermal method,the catalyst surface defects increased,the electron hole increased,thus the TiO₂-Yb-Cu catalyst with small particle size,high crystallinity,agglomeration of small and large specific surface area,as a result it had high photocatalytic activity.And more the TiO₂-Yb-Cu catalyst prepared by microwave hydrothermal method had low fluorescence intensity,which indicated that the copper and ytterbium doped could inhibit the recombination of photogenerated electron hole,led to the TiO₂-Yb-Cu catalyst had high photocatalytic activity.At the same time,the TiO₂-Yb-Cu catalyst had higher photocatalytic activity when the relative mass fraction of rutile phase and anatase phase was respectively 0.6%and 99.4%.The results of this paper showed that the TiO₂-Cu,TiO₂-Yb and TiO₂-Yb-Cu catalysts prepared by microwave hydrothermal method had high photocatalytic activity,and microwave enhanced the photocatalytic activity of the catalysts.Microwave hydrothermal method combined the traditional hydrothermal synthesis method with the microwave field,and used its high temperature and high pressure reaction environment to dissolve some of the difficult substances,and then photocatalyst was prepared by recrystallization,separation and calcination at high temperature.Thisprovidesanenergy-saving,high-efficiencyand environment-friendly green pathway for the preparation of doped TiO₂ photocatalyst,which promotes the practical application of TiO₂ photocatalyst and enriches the research content of microwave chemistr.