Synthesis Of CaTiO₃ Photocatalyst And Its Doping Modification

With the increasingly serious environmental pollution problems,the traditional methods cannot efficiently solve the pollution problem,especially water pollution.At present,the photocatalytic degradation of organic pollutants is a new way,it is cheap,efficient,and will not bring secondary pollution in the process of solving the problem of water pollution.How to obtain the photocatalyst with high efficiency is the key factor in degradating organic pollutants.The methods of improving the activity of photocatalyst mainly include ion doping,semiconductor recombination and noble metal deposition.It is found that doping is a effective method to improve the activity of photocatalyst,which is also an active aspect in photocatalytic field.In this paper,the butterfly-like CaTiO₃ is prepared by combining melting alkaline method with hydrothermal method.Then,ion doping used to enhance photocatalytic activities of CaTiO₃ photocatalysts.The phase and structure of Ca TiO3 are identified by XRD、SEM and TEM.The optical performance of CaTiO₃ is measured diffusing reflectance ultraviolet-visible（UV-vis）absorption spectrum and photoluminecence（PL）.The photocatalytic activity of CaTiO₃ is measured by decomposing methylene blue（MB）solution.The main results of this paper include:（1）By changing the reaction conditions such as temperature,time and concentration of mineralizer,we found that the optimum reaction conditions are 0.25 M NaOH concentration and180oC reaction for 4 h.The results show that the morphology of CaTiO₃ with rectangular prism and butterfly-like is determined by the concentration of cationic and anionic OH-of mineralizer.The band gap of the sample is 3.61 eV measured by UV-visible diffuse reflection.（2）No new phases are introduced at A-site Ag⁺-doped Ca TiO3,and the morphology of the sample is unchange,while the grain size is reduced.UV-visible diffuse reflectance analysis shows that Ag⁺ doping Ca TiO3 can increase the absorption of visible light,reduce the band gap and improve the photocatalytic activity.The results of A-site La3+-doped CaTiO₃ shows that La3+doping Ca TiO3 can not increase the absorption of visible light.The photocatalytic activity of Ca TiO3 is reduced by the doping of a small amount of La3+（x=0.01-0.04）.While the grain size is reduced and the photocatalytic performance of CaTiO₃ is improved by the doping of microscale La3+（x=0.0005-0.005）.The optimum doping amount of La3+ is x= 0.001.（3）No new phases are introduced at B-site Zr⁴⁺-doped Ca TiO3,the morphology and the grain size of the sample is unchange.UV-visible diffuse reflectance analysis shows that Zr⁴⁺ doping Ca TiO3 can not increase the absorption of visible light.The sample photocatalyst performance improved by the Zr⁴⁺ capture photogenerated electrons,hindering the recombination of the photo-generated electron-hole pairs.The B-site Fe³⁺-doped CaTiO₃ shows that the morphology and the grain size of the sample is unchange and can not increase the absorption of visible light.The photocatalytic activity of CaTiO₃ is reduced by the doping of a small amount of Fe³⁺（x=0.01-0.04）,while the microscale doping（x=0.0008-0.005）effectively enhanced the photocatalytic performance of CaTiO₃.The optimum doping amount of Fe³⁺ is x=0.0017.