The Study On The Photocatalytic ?Photoelectrocatalytic? Degradation Of Organic Pollutants By CdTe/TiO₂ Nanotubes

Titanium dioxide?TiO₂?materials have the characteristics of low cost,strong oxidizability and photochemical stability.TiO₂ has broad application prospects in environmental protection and new energy.With the development of society,environmental problems caused by refractory pollutants such as volatile organic compounds?VOCs?and water-soluble phenolic substances have become increasingly serious.The treatment of such degraded pollutants by TiO₂ photocatalysis technology has gradually become a hot spot of research.The wide band gap of TiO₂,the high recombination rate of photogenerated electrons?e^-?and holes?h⁺?limit its application.Based on the preparation of TiO₂ NTs array by anodization,a new process for narrow-bandgap semiconductor CdTe QDs doped TiO₂ NTs arrays with enhanced visible light response and photocatalytic activity was developed.In this paper,the photocatalytic performance of CdTe/TiO₂ NTs array for gas phase toluene and the photocatalytic performance of 4-chlorophenol were investigated.The main contents are as follows:?1?TiO₂ NTs arrays and CdTe/TiO₂ NTs arrays were successfully prepared by anodization and electrochemical deposition.The EDS test,i-t curve test,Mott-Schoctty test and so on prove that CdTe/TiO₂ NTs array has stronger visible light response and photocatalytic activity than TiO₂ NTs array.This experiment explores the various process parameters in the preparation of the catalyst.When the anodization voltage is 60V,the oxidation time is 120min,the annealing temperature is 550°C,etc.,the photocurrent of the TiO₂ NTs array can reach 1.0 mA·cm^-2.The photocurrent of the CdTe/TiO₂ NTs array can reach 1.4 mA·cm^-2 when the deposition time is 4 min.?2?This experiment explored the catalytic performance of TiO₂ NTs array and CdTe/TiO₂ NTs array in photocatalytic gas phase toluene under simulated sunlight.The results show that the CdTe/TiO₂ NTs array has strong photocatalytic properties for gas phase toluene.The catalytic ability of CdTe/TiO₂ NTs arrays is much stronger than that of TiO₂NTs arrays.The degradation rate of CdTe/TiO₂ NTs array after photocatalytic toluene was65.9%.This is because a large amount of radicals such as·O^2-,·OH are generated on the surface of the catalyst during photocatalysis.This is capable of rapidly degrading toluene.When the CdTe/TiO₂ NTs array photocatalytic toluene was found in the cycle repeat experiment,the degradation efficiency increased gradually with the increase of the number of cycles.,the degradation efficiency increased gradually with the increase of the number of cycles.According to the characterization analysis,it may be that the surface functional group of the electrode material reduces the activation energy of the reaction.Perhaps it is because of the increase in the number of experiments in the cycle experiment,·O^2-and·OH also gradually increased.?3?Based on the above material characterization and photocatalytic gas phase toluene effect,the catalytic performance of photo-catalyzed 4-chlorophenol on CdTe/TiO₂ NTs array was studied.Photodegradation of CdTe/TiO₂ NTs array can achieve 74.2%degradation rate in 5h.This proves that the CdTe/TiO₂ NTs array has strong photoelectrocatalytic activity for 4-chlorophenol.Influencing factors analysis experiments explored the best experimental conditions in the photoelectrocatalytic process.Repeatability experiments confirmed that the CdTe/TiO₂ NTs array has good photoelectrocatalytic stability.The efficiency of photocatalytic 4-chlorophenol in the CdTe/TiO₂ NTs array is more than twice that of photocatalytic efficiency.This is due to the fact that the photoelectrocatalytic plus positive bias conducts photogenerated electrons,which results in the catalyst retaining more·OH and h⁺.Therefore,the photocatalytic performance is far stronger than the photocatalytic performance.