Preparation And Photocatalytic Properties Of Titanium Based Nanofibers

Nowadays,we are facing that energy consumption and environmental crisis have become the two major challenges.Therefore,it is urgent to find a sustainable clean energy.Using solar energy to produce green energy,treat sewage and solar cells to solve the two major problems of energy consumption and environmental crisis.As one of the green renewable energy,solar energy can be used efficiently,such as converted into electric energy,chemical energy and so on.Therefore,through the photocatalysis of semiconductors,solar energy can be transformed into chemical energy,give full play to its unique advantages,and effectively solve the current energy and environmental problems.Titanium dioxide(TiO₂)nano materials are widely used in the field of photocatalysis due to stability,high efficiency,low energy consumption,reusability and low cost.However,the wide band gap of TiO₂,it can only be activated under ultraviolet light with a wavelength less than 387 nm.Therefore,TiO₂can only absorb ultraviolet light(about 5%of solar energy),which greatly limits its photocatalytic performance.Boron carbon nitrogen(BCN)has narrow band gap and large light absorption range,but its photogenerated electron hole pair recombination is faster.When a heterojunction is formed between BCN and semiconductor,the heterojunction has an appropriate band gap,increases the light absorption range,promotes the separation and transfer of charge and improves the photocatalytic performance.Electrospinning technology is widely used in biomedicine,military industry,chemical industry,information,electronics and other fields because of its advantages of low cost,large specific surface area,controllable size,wide applicability of raw materials and convenient operation.In the field of photocatalysis,electrospinning nanofibers have been widely used due to their high specific surface area,which can provide more active sites for photocatalysis.In view of the above problems,nanofiber catalysts for photocatalytic degradation and hydrogen peroxide production were prepared by different methods with the help of electrospinning technology.Specifically,it includes the following two aspects:(1)TiO₂/PVP nanofiber membrane was prepared by electrospinning with isopropyl titanate as titanium source and PVP as carrier.TiO₂ nanofibers were obtained by calcining the nanofiber membrane,and then BCN/TiO₂ composite nanofibers were prepared by solvent evaporation.The photocatalytic activity of methylene blue(MB)and Rhodamine B(RhB)dyes was evaluated by simulating sunlight degradation.By changing the quality of melamine and boric acid crystalline powder and changing the loading amount of BCN on TiO₂ nanofibers,the results show that the photocatalytic degradation performance of 0.1-BCN/TiO₂ composite nanofibers is the best.When exposed to light for 20 min,the degradation rate of MB dye(30 mg L^-1)by0.1-BCN/TiO₂ composite nanofibers reaches 99%,the rate constant of 0.1-BCN/TiO₂composite nanofibers(K=0.25787 min^-1)is 29.303 times of BCN(K=0.0088 min^-1)and 3.1828 times of TiO₂ nanofibers(K=0.08102 min^-1).When exposed to light for 30min,the degradation rate of RhB dye(20 mg L^-1)by 0.1-BCN/TiO₂ composite nanofibers reaches 99%,the rate constant of 0.1-BCN/TiO₂ composite nanofibers(K=0.13656min^-1)is 39.9298 times of BCN(K=0.00342 min^-1)and 4.0898 times of TiO₂ nanofibers(K=0.03339 min^-1).(2)TiO₂/PVP nanofiber films were prepared by electrospinning with isopropyl titanate as titanium source and PVP as carrier,and then V-BCN/TiO₂ composite nanofibers were prepared by vapor deposition.The photocatalytic activity was evaluated by simulating sunlight to produce hydrogen peroxide.By changing the quality of melamine and boric acid crystalline powder and changing the loading amount of BCN on TiO₂ nanofibers.The results show that the photocatalytic hydrogen peroxide production performance of 1.5V-BCN/TiO₂ composite nanofibers is the best,and the hydrogen peroxide production of 1.5V-BCN/TiO₂ composite nanofibers is 12.22 times that of pure TiO₂.With the increase of the doping amount of BCN,the photocatalytic hydrogen peroxide production performance is better,and with the further increase of the doping amount of BCN,the photocatalytic activity decreases.This is the addition of an appropriate amount of BCN can promote the photogeneration of electrons.In addition,the increase of specific surface area and active sites can also improve the photocatalytic activity.