Design And Preparation Of Titanium Dioxide-based Photocatalysts And Study On Photocatalytic Performance

More than 15%of the world’s population lacks access to reliable water sources essential forpublic health,and nearly 1.8 million people die each year from waterborne diseases.There is an urgent need to develop a safe,stable and cost-effective new disinfection technology to mitigate bacterial infections caused through water.So far,various methods,including ultraviolet light,chlorination,ozone and photocatalysis,have been used to disinfect water.In contrast,photocatalysis technology based on solar energy shows unique characteristics in environmental applications.Photocatalysis not only kills bacteria,but also produces clean energy fuels such as hydrogen（H₂）.The development of efficient,non-toxic and multifunctional photocatalysts is the focus of current research.TiO₂,g-C₃N₄ are the most studied photocatalysts,but there are also some problems,such as high photogenerated carrier recombination rate and narrow optical absorption range.In this paper,2D/2D TiO₂/Bi₂O₃,3D/3D TiO₂/BiOCl_0.7I_0.3-P and 2D/0D TiO₂/Ni were prepared by modifying the traditional semiconductor TiO₂.Detailed research contents and conclusions are as follows:（1）2D TiO₂ nanosheets were designed and prepared,which were combined with 2D Bi₂O₃nanosheets by hydrothermal method to form 2D/2D TiO₂/Bi₂O₃ S type heterojunction with large contact interface.The S-type heterojunction charge transfer mode was an important factor to improve the photocatalytic performance,which accelerated the separation of photogenerated carriers and ensured the strong redox ability of TiO₂/Bi₂O₃ photocatalysts.Good interfacial contact improved the efficiency of space charge separation and exposed more active sites.Under the irradiation condition of 365 nm LED light source,the hydrogen production performance of the composite sample was up to 12.08 mmol·g^-1·h^-1,which was 43 times that of pure TiO₂.Moreover,the composite sample had good inactivation activity against Escherichia coli（E.coli）under the irradiation of full spectrum Xenon lamp.（2）TiO₂/Ni photocatalyst was synthesized by calcination process using TiO₂ nanosheets as substrate by depositing non-precious metal Ni on the surface of TiO₂ nanosheets.Ni single atom and Ni cluster were observed,resulting strong charge transfer and photothermal effect for enhacing the photocatalytic performance of TiO₂.The optimal sample TN-60 can produce 5.19 mmol·g^-1·h^-1 hydrogen under full spectrum Xenon lamp irradiation,and can kill E.coli under 808 nm light irradiation.（3）Hollow TiO₂ was prepared using SiO₂ spheres as templates,and TiO₂/BiOCl_0.7I_0.3 was synthesized by in-situ growth of BiOCl_0.7I_0.3 S-heterojunction photocatalyst with the help of polyvinylpyrrolidone（PVP）in oil bath.Under the condition of full spectrum Xenon lamp irradiation,TiO₂/BiOCl_0.7I_0.3-P photocatalyst can not only almost completely degrade Rhodamine B（Rh B）,but also effectively degrade tetracycline hydrochloride（TC）and ofloxacin（OFX）within10 min,indicating its universal applicability to degradea variety of pollutants and a high inactivity against E.coli and Staphylococcus aureus（S.aureus）.