Preparation And Photocatalytic Degradation Performance Of Titanium Dioxide Based Metal-organic Framework Composites

Environment and energy are critical subjects for sustainable human development.Photocatalysis,a green and environmentally friendly method,can be used for the degradation of pollutants in the environment due to its low cost and high photocatalysis activity.Anatase titanium dioxide（TiO₂）has great potential in photocatalysis because of its chemical stability,low cost,non-toxicity,and low environmental impacts.Nevertheless,photocatalytic effect is refrained due to its inherent defects such as a single response only to UV light and poor separation efficiency of photogenerated electron-hole pairs.Doping and heterojunction are effective methods for its modification.In this study,we successfully prepared photocatalysts based on TiO₂ composited with metal-organic frameworks through doping and constructing heterojunctions to enhance photocatalytic properties.1.We have successfully prepared TiO₂/UiO-67 photocatalyst through an in-situ solvothermal method.The optimal doping ratio of T-10%U is obtained by optimizing the ratio.The degradation rate of aflatoxin B1（AFB1）is 98.9%only in 80 min,which is higher than most of the reported photocatalysts under visible light irradiation.In addition,the T-10%U photocatalyst showed excellent recyclability.We demonstrated that the enhanced photocatalytic mechanism was owing to the heterojunction between TiO₂ and UiO-66,which enhanced effectively the separation of photogenerated charge carriers and visible light response.The hydroxyl radical（·OH）,hole（h⁺）and and the superoxide radicals（·O₂ˉ）were active groups in photocatalysis and then oxidized AFB1 to some small molecules to achieve the degradation of AFB1.2.TiO₂(Fe³⁺)/UiO-66 photocatalysts were successfully prepared by the sample situ solvothermal method.The degradation rate of T-Fe-4%U for TCH is 98%within 25min.The photocatalytic performance of T-Fe-4%U is superior to the commercial P25 and most of the reported photocatalysts under visible light irradiation.In addition,T-Fe-4%U with excellent stability and photocatalysis activity.The improved photocatalytic activity of TiO₂(Fe³⁺)/UiO-66 can be attributed to two main factors:（1）Firstly,visible light response is improved due to the doping of Fe element;（2）the Z-scheme heterojunction of TiO₂(Fe³⁺)/UiO-66 which has matched energy band structures leads to efficient separation and transfer of photogenerated electron-hole pairs and retain a more negative reduction potential and a more positive oxidation potential,promoting generation of the main active species including·O₂^ˉ,h⁺,and·OH and enhancing degradation of tetracycline hydrochloride.