Energy Band Engineering And Photocatalytic Property Study Of Titanium Dioxide Thin Films

The global economy,the environmental pollution caused by population growth,and the depletion of fossil fuels have caused human society to face a series of energy problems.It is an essential problem for humankind to search for a renewable,cheap and clean energy source.Among them,the hydrogen energy,which can be stored and transported,is an advantageous clean renewable energy source.In recent decades,hydrogen energy,a new energy source that solves the current difficulties faced by mankind,has become an object of extensive research in various countries.Photocatalytic technology accelerates the process of cracking pure water into hydrogen and oxygen by using the endless solar and semiconductor catalysts.However,due to the band gap and internal carrier recombination of semiconductor catalysts,lower quantum efficiency is caused,thereby limiting the photocatalytic activity.Base on it,a series of energy band engineerings on Ti O₂ thin films were proposed in order to the absorption capacity of the catalyst and the electron-hole separation capacity improves,and the number of carriers involved in the photocatalytic reaction increases.（1）Ti³⁺doped energy level.The Ti³⁺self-doped Ti O₂ thin film was realized by adjusting the oxygen flow during electron beam evaporation.With the increase of oxygen flow,the content of Ti³⁺was effectively regulated,and the hydrogen production of Ti O₂ thin film samples was regulated.In addition,it was also found in the experiment that the oxygen partial pressure in the vacuum chamber was different due to the different oxygen intake flow during the film deposition process,which led to the different crystallinity of Ti³⁺self-doped thin films with different contents at the same temperature in subsequent annealing experiments.（2）Rutile/anatase heterojunction.The rutile/anatase heterojunction was made by laser pulse denudation in acetone solution,and then the anatase/anatase heterojunction was prepared by electron beam evaporation and annealing.With the increase of laser beam power,the amount of heterogeneous junction was effectively increased,and the photocatalytic activity of the sample was regulated.This is because the band difference between the heterojunction leads to carrier migration,which is conducive to carrier separation.（3）Cu₂O/Ti O₂heterogeneous junction.Employing laser pulse denudation in atmospheric environment,a layer of nanoparticles is directly decorated on the Ti O₂ thin film deposited by an electron beam to obtain Cu₂O/Ti O₂heterogeneous junction.This is because of the high concentration of holes on the surface of Cu₂O and the high concentration of electrons on the surface of Ti O₂.Moreover,the potential difference formed by the photogenic charge accumulated at the two ends of the disjunction can be used as a driving force to effectively decompose the photogenic charge.