Preparation Of TiO₂ Nanofiber Composite Films And Investigation On Photoelectrocatalytic Performance

Nowadays,the rapid growth of industry has caused great pressure on resources and the environment.Sustainable development has become an inevitable choice in this time.Therefore,it is extremely urgent to dispose of industrial sewage efficiently and realize the recycling of water resources.Photoelectrocatalysis is a green and environmental-friendly water treatment technology,which combines with the advantages of photocatalysis and electrocatalysis,and could completely degradate pollutants into CO₂ and H₂O.Developing photoelectrocatalysis technology of high performance catalytic materials is the key to realize practical application.Due to the advantages of stable physical and chemical properties,cheap and non-toxic,the traditional material TiO₂ has been a hotspot in the field of photoelectrocatalysis.However,its practical application is limited due to its poor ability of visible light absorption,low utilization rate of sunlight and high electron-hole recombination rate.Therefore,in order to improve the photoelectrochemical performance of TiO₂,Cu₃P/TiO₂ and CdSe/C/TiO₂ composite systems were constructed,and the composition,photoelectric characteristics,photodegradation performance and activity enhancement mechanism of the samples were analyzed.The main contents are as follows:(1)Firstly,TiO₂ nanofiber film was prepared by basic solvothermal method,and then Cu₃P/TiO₂ heterojunction photoelectrocatalyst was synthetized by in-situ alcohol solvothermal method.The introduction of Cu₃P not only expands the visible absorption range of the system,but also reduces the charge transfer resistance,resulting in higher photocurrent density and open circuit voltage.Under irradiation of 300 W Xe lamp,0.06-Cu₃P/TiO₂ sample processes the most excellent transient photocurrent(17.12(?)A·cm^-2),which is about 3.2 times than that of TiO₂.After 120 min irradiation,the degradation rate of methylene blue(MB,5 mg·L^-1)is 88.36%for 0.06-Cu₃P/TiO₂,which is 17.07%higher than that of pure TiO₂.After four successive cycles,the degradation rate of MB decreased slightly.In addition,the energy band structure analysis and radical trapping experiment results show that the p-n heterojunction is formed between Cu₃P and TiO₂,which effectively promotes the carrier separation and migration,and significantly improves the photoelectrocatalytic degradation activity.(2)Carbon membrane and CdSe were loaded on the surface of TiO₂ nanofiber film(CdSe/C/TiO₂)by in-situ solvothermal deposition.The current density of CdSe/C/TiO₂ is45.36(?)A·cm^-2,which is both higher than that of C/TiO₂(29.52(?)A·cm^-2)and CdSe/TiO₂(16.16(?)A·cm^-2),even 9 times of pure TiO₂.Under 120 min irradiation,MB degradation rate is 92.43%for CdSe/C/TiO₂,which is 21.14%higher than that of pure TiO₂.The degradation efficiency of MB decreased slightly after recycling for four times.At the same time,it is found that the introduction of carbon membrane not only provides a charge transfer channel,which is conducive to the electron migration from CdSe to TiO₂,but also improves the contact performance between the composite film and electrolyte.On the one hand,the synergistic effect of carbon membrane and CdSe makes the ternary system capture more visible light and produce more carriers.On the other hand,it promotes the rapid transfer of holes to the electrode surface,at the same time,the holes can quickly and effectively participate in the oxidation degradation of dyes by improving the contact performance with the reaction solution,which further improves the photoelectrocatalytic activity of TiO₂nanofiber film.