Investigation On Photoelectrocatalytic Degradation Dyes Of TiO₂ Nanotube Arrays Based Composite Materials

Recent years,the purification of environmental pollutants has become a hot topic that needs to be solved urgently all over the world.Photoelectrocatalytic technology can produce active radicals with strong oxidizability to decompose organic pollutant into CO₂and H₂O completely.Photoelectrocatalytic technology,combined with the advantages of photocatalysis and electrocatalytic technology,has become one of effective strategies to solve water pollution problem,due to the advantages of simple operation and non-pollution.As a functional inorganic semiconductor material,TiO₂ has the advantages of suitable band structure,no toxicity,stable physicochemical properties and low price,and has been widely studied in the field of photoelectrocatalysis.In this dissertation,the photoelectrochemical degradation performance of TiO₂ nanotube arrays（TiO₂ NTAs）was enhanced by loading cocatalyst and semiconductors,and applied to degrade organic pollutants.The main contents and results are as follows:（1）TiO₂ NTAs was obtained by the two step anodization method,and the perpared sample was decorated with Co₂P NPs by the hydrothermal method.Compared with TiO₂NTAs and other perpared samples,1.5-Co₂P/TiO₂ NTAs exhibits the highest transient photocurrent density of 0.39 m A·cm^–2,which is 3.22 times higher than that of pure TiO₂NTAs,and it’s the most active photoanode in the degradation of 5 mg·L^–1 MB or Rh B with degradation rate at 88.73%and 57.27%within 90 mins under（350–780 nm）300 W Xe lamps irradation,respectively.Radical trapping experiments revealed that·OH is the main active radical during the degradation processes.Photoelectric analysis revealed that Co₂P as a cocatalyst can provide charge capture sites and promote the transfer of photogenerated holes,which greatly improve the photoelectrocatalytic performance of the system and the degradation efficiency of organic pollutants.（2）SnO₂/TiO₂ heterojunction was constructed by the in-situ hydrothermal method,0.7-SnO₂/TiO₂ NTAs exhibits the highest transient photocurrent density of 0.94 m A·cm^–2,which is 4.48 times higher than that of pure TiO₂ NTAs.And the removal efficiencies of 5mg·L^–1 MB or Rh B could reach 94.71%and 80.58%in 90 mins under（350–780 nm）300W Xe lamps irradation,which is 1.26 times and 1.72 times higher than that of pure TiO₂NTAs,and the photoelectrocatalytic performance is still stable after four cycle experiments.Moreover,radical trapping experiments,photoelectric tests and active radicals analysis revealed that Z-scheme heterojunction can effectively promote carriers separation and migration,while retaining the strong redox ability of the heterojunction.MB and Rh B can be oxidized into CO₂,H₂O and other intermediates by·O₂^-,·OH and holes.·O₂^-is the main active radical during the degradation processes,which plays an important role in the PEC degradation.