Study On The Preparation And Photocatalytic Properties Of Ti³⁺ And N Self-doped Nano SrTiO₃

SrTiO₃ semiconductor photocatalyst attract more attention because of its excellent performance,which can degrade organic pollutant and produce H₂/O₂ under light.However,because of the wide band gap of SrTiO₃,the visible light can not be used,and the recombination rate of photogenerated carriers is high,noble metal catalysts need to be loaded in order to have hydrogen production activity,which limits its application.Recent studies have shown that the use of Ti³⁺defect self-doped SrTiO₃ can expand its visible light activity and hydrogen production activity without noble metal catalysts,which has become a research hot point.However,these defects are difficult to prepare,difficult to stabilize and so on.In view of the existing problems in the preparation of such defects by reduction method,this paper proposes a new way to construct Ti³⁺-N self-doped SrTiO₃ photocatalyst by oxidation method,which can have hydrogen production activity without co-catalyst and enhance its visible photocatalytic degradation activity.Through the study of photocatalytic mechanism,preparation of photocatalyst and modification of photocatalyst,Ti³⁺-N self-doped nano SrTiO₃ photocatalysts prepared by direct oxidation of hydrogen peroxide and alkali thermal oxidation were systematically explored,and the degradation and hydrogen production of samples were evaluated.The results show that Ti³⁺-N self-doped nano SrTiO₃ photocatalyst prepared by direct oxidation of H2O2 has absorptive properties in the range of 400-800 nm,and the sample has the activity of hydrogen production without co-catalyst.In addition,La/Pr-N co-doped nano SrTiO3 photocatalyst was successfully prepared by microwave hydrothermal method.It was found that the samples had good visible light absorption characteristics.The main conclusions of this paper are as follows:1.Ti3+-N self-doped nano SrTiO3 photocatalyst was successfully prepared based on the oxidation of hydrogen peroxide.The photocatalyst was characterized by X-ray diffraction and transmission electron microscopy,and the formation mechanism was studied.By adjusting the atmosphere and heat treatment temperature,we can obtain amorphous and crystalline Ti³⁺-N self-doped nano SrTiO₃ samples.The results show that the V-5-T-200-Air sample has high hydrogen production activity without co-catalyst,and the hydrogen production rate is 8.3 times as high as pure nano SrTiO₃.V-20-T-130-Vac sample has good visible-light photocatalytic degradation performance.Compared with pure nano SrTiO₃,the photocatalytic degradation rate is increased by 9.5 times,and the stability of catalyst recycling is higher.2.Ti³⁺-N self-doped nano SrTiO₃ photocatalyst was successfully prepared under alkali-thermal conditions.When the heat treatment condition is 200°C-72h,the samples have good crystallinity and good response to visible light.3.The La/Pr-N co-doped nano SrTiO3 photocatalyst was successfully prepared by microwave hydrothermal method.When the treatment conditions were 200°C-5h,the samples doped with 15%La/Pr had good light response ability in the visible region,which made a good foundation for improving the photocatalytic performance of SrTiO₃.