Charge Separation Enhanced Photocatalytic Decomposition Of Benzene By Branched TiO₂ Nanorod Array

Photocatalytic technology has been considered as an effective method for the degradation of volatile organic pollutants indoor.Research has focused on improving the activity of photocatalyst in the field.This article aimed at promoting photo-induced charge separation.Firstly,single crystal titanium dioxide nanorods array were prepared through one-step hydrothermal method,then TiO₂ nanoparticles were fabricated onto the TiO₂nanorods by a chemical bath deposition method at room temperature to obtain nanorod@nanoparticle core-shell structure?TNR@TNP?.By controlling the time of chemical bath process,we found the TNR@TNP of 30h show the best performance of the photocatalytic degradation of benzene.The performance of photocurrent test and XPS analysis indicated that the nanoparticles located at the TiO₂ nanorods,have lots of oxygen vacancy defects at their rough surfaces.The holes were trapped on the nanoparticles by the oxygen vacancy defects and the electrons were transferred to the FTO substract rapidly,enhancing the separation of electrons and holes.So the photocatalytic activity of TNR@TNP was significantly improved.In order to further improve the separation of photo-induced charge,an annealing treatment on titanium dioxide nanorods array was taken at 450^oC under ammonia atmosphere which served as nitrogen source,and then TiO₂ nanoparticles were fabricated onto the TiO₂ nanorods.XPS results showed that N element has enterd to substitutional site during the annealing process.The nitrogen doping nanorods@nanoparticles core-shell structure showed better performance of the photocatalytic degradation of benzene than that of nanorods@nanoparticle core-shell structure?TNR@TNP?.UV and UPS characterization revealed that the conduction band position of nitrogen doped TiO₂ nanorods was more positive than that of TiO₂ nanoparticles,implying that the barrier potential difference became larger when the electrons migrated from the conduction band of TNP to that of N-TNR.The charge separation was greatly increased and the photocatalytic activity was improved.In conclusion,this paper focused on the charge separation efficiency of catalytic material to obtained good photocatalytic activity of photocatalyst,through constructing TNP@TNR core-shell structure.Single crystal TiO₂ nanorods could serve as a high-speed electron transport channel and the nanoparticles on the surface as a hole capture trap.Then the performance of photocatalytic degradation of benzene by TNR@TNP was further improved through doping nitrogen element into TiO₂ nanorods array,because the separation of charge was promoted by increasing the potential barrier difference between the conduction band of nanoparticles and that of nanorods.This work provided a photocatalytic material easier to load,took further study on the charge transfer behavior,and provided a quotable method for research in the relative field of photocatalysis.