Preparation Of Ag₃PO₄/TiO₂ Photocatalyst And Its Photocatalytic Activity

Nowadays,environmental pollution and energy shortage are two major worldwide problems which need to be solved urgently.It is extremely pressing to develop new and clean energy,and semiconductor photocatalysis is one of the vital ways to solve this problem.TiO₂ is the most widely used semiconductor in the photocatalytic process,but its low separation efficiency of photogenerated electron-hole and wide band gap together limits its application.In order to further increase the separation efficiency,the synthesis of titanium dioxide with high activity of 001 facet is one of the effective methods.In this thesis,titanium dioxide with high content of active 001facet was prepared by using common hydrazine hydrate as a capping reagent,and its formation mechanism and photocatalytic mechanism were discussed.Using Na₄P₂O₇ as precursor,the highly active Ag₃PO₄ with multi-morphological structure was synthesized by means of kinetic and thermodynamic control.The mechanism of photocatalytic oxygen generation of Ag₃PO₄ was also analyzed.At last,the heterostructure photocatalyst prepared by combining the two photocatalysts mentioned above which can not only make TiO₂ response to visible light but improve the stability of Ag₃PO₄.The main research contents are as follows:1.TiO₂ with high activity 001facet was synthesized using S as raw material and butyl titanate as titanium source by a simple solvothermal method.By adjusting different T/N ratios,calcination temperatures and hydrothermal temperatures,and using XRD,XPS and TEM to characterize,it was found that,under simulated sunlight,the photocatalytic hydrogen production activity of TN120-600 loading 0.5 wt.%Pt was the highest,which was as high as 8.435mmol·g^-1·h^-1,and 7 times higher than A-TiO₂ and1.45 times higher than P25.2.Using sodium pyrophosphate?Na₄P₂O₇?and silver nitrate?AgNO₃?as precursors,silver phosphate with multiple morphologies were synthesized by a simple hydrothermal method.Silver phosphate with cubic and dodecahedral structures were synthesized by thermodynamic control.By means of thermodynamic control,the dodecahedral,spherical,rough spherical Ag₃PO₄ were synthesized,and their photocatalytic oxygen production capacities were studied.It was found that the oxygen production capacity sequence was listed successively:rough spherical>dodecahedral>granular,and the oxygen production capacity of rough spherical Ag₃PO₄ was up to856.06?mol·h^-1·g^-1.3.Through adjusting the different load mount of TiO₂,Ag₃PO₄/TiO₂ heterojunction photocatalyst prepared by an in-situ growth method.XRD,XPS and SEM were used to characterize the samples,It was found that 20 wt.%Ag₃PO₄/TiO₂ have the strongest degradation ability towards MO,after 40 min,the degradation efficiency was as high as 95%,the degradation rate constant was 10 times as that of TiO₂,1.9 times as that of Ag₃PO₄,after four cycles,the degradation rate was still as high as 87%.