Construction Of TiO₂-based Z-type Heterojunction And Its Photocatalytic Properties

Photocatalytic technology is one of the most effective ways to solve the problems of energy shortage and environmental pollution,and the design and preparation of high-efficiency photocatalytic materials is of great significance.Heterostructures can effectively improve the optical response range of semiconductor materials,promote the effective separation of photogenerated carriers,and thereby improve quantum efficiency and photocatalytic activity.In this paper,hollow spherical shaped R-TiO2/A-TiO2 Z-type heterostructures,plasma enhanced ternary Z-type heterostructures of TiN/A-TiO2/R-TiO2,and dual Z-type A-TiO2/R-TiO2/Cu2O heterostructures were successfully prepared by hydrothermal methods combined with non-metallic B-element doping,hydrothermal in-situ oxidation,and solution reduction methods.The composition,microstructure,light absorption,photoelectric properties,and photocatalytic properties of the samples were studied by using characterization methods such as X-ray diffraction,transmission electron microscopy,photoelectron spectroscopy,transient photocurrent and so on.The relationship between microstructure,composition,and properties was established.It provides ideas for optimizing the performance of various semiconductor photocatalytic materials.The main results are summarized as follows:(1)A hollow spherical R-TiO2/A-TiO2 Z type heterogeneous junction photocatalytic material was successfully prepared by hydrothermal method combined with element B doping.The band structure and oxygen vacancy content can be successfully tailored by controlling the amount of B dopant.The photocatalytic performance was enhanced due to the Z-scheme transfer path formed between the B doped anatase-TiO2 and rutile-TiO2,optimized band structure with markedly positively shifted band potentials,and the synergistically slow photon effect.In addition,optimization studies have shown that when the mass ratio of B doping amount to TiO2 is 0.5:1,the weight ratio of R-TiO2 to ATiO2 is 0.070,achieving the highest photocatalytic performance.The optimal degradation rate is 0.0382 min-1,which is three times as high as that of commercially available P25 samples.(2)A plasma enhanced(A,R)-TiO2/TiN ternary Z-type heterojunction photocatalyst was successfully prepared by in-situ oxidation of TiN using a hydrothermal method.By regulating the amount of H2O2 oxidant in the hydrothermal process,the three-phase content of TiN,A-TiO2,and R-TiO2 can be adjusted.The photocatalytic performance was enhanced due to the the plasma resonance effect of TiN,the N-O bond connected charge transfer channel at the TiO2/TiN heterointerface,and the synergistically Z-scheme transfer path formed between the A-TiO2 and R-TiO2.The optimization study showed that when the three-phase mass ratio of A-TiO2:R-TiO2:TiN was about 15:1:1,the photocatalytic performance of the sample was optimal,with a degradation efficiency of over 97%under 90 minutes of visible illumination.(3)On the basis of obtaining a Z-type R-TiO2/A-TiO2 heterojunction,a polyhedral spherical shaped narrow gap semiconductor Cu2O particles were successfully prepared by hydrothermal method,and TiO2 was tightly and uniformly loaded onto its surface,resulting in the preparation of a double Z-type A-TiO2/R-TiO2/Cu2O photocatalytic material.By adjusting the content of Cu2O,the light absorption range,energy band structure,and photoelectric performance of the sample can be controlled.The research shows that When the molar ratio of Cu2O to TiO2 is 0.75,the photocatalytic degradation rate of the catalyst over tetracycline hydrochloride can reach over 90%after 150 min of illumination,which is 7.95 times higher than that of the sample without loaded Cu2O.