Study On The Photocatalytic Reduction Performance Of N-doped Titanium Oxide Films With Noble Metal Modification

Photocatalytic reduction technique should be one of the possible solutions to the problem of ultra-low concentration of heavy metal pollution.Titanium dioxide?TiO₂?has been widely investigated as semiconductor photocatalysts,for its high photocatalytic activity and corrosion resistance.However,it can just absorb ultraviolet light for its wide band gap?3.2eV?meanwhile has low quantum efficiency.In this paper,visible-light photocatalysis reduction properties of nitrogen-doped titanium dioxide films with noble metal?Ag and Pd?modification were investigated,especially in terms of the role played by noble metal modification.Nitrogen-doped titanium dioxide?N-TiO₂?thin films were prepared by DC magnetron sputtering technique.The parameters as following:nitrogen partial pressure 80%,substrate temperature 250?,sputtering gas pressure 0.5Pa of N-Ti02 films has the best photocatalytic reduction property.On the basis of this,several Ag-N-TiO₂ films and Pd-N-TiO₂ films with variable noble metal contents were prepared.Experimental results showed that Ag-N-TiO₂ films prepared were single anatase phase.With the Ag modification,the particle size of thin film increases,and the surface becomes rough and loose.UV-Vis absorption edge moves from 350nm to 380nm.Ag atom existed in the form of Ag+ in Ag-N-TiO₂,and Ti atom existed in the form of Ti4+ and Ti3+.The visible light absorption property is enhanced.The Ag-N-TiO₂ film with 6.21 At.%of Ag has the best photocatalytic reduction property.Pd-N-TiO₂ films prepared were also single anatase phase.With the Pd modification,the particle size of thin film increases,and the surface becomes rough and loose.UV-Vis absorption edge moves from 350nm to 400nm.Pd atom existed in the form of Pd and Pd2+ in Pd-N-TiO₂.The visible light absorption property is enhanced.With the increase of Pd content,the photocatalytic reduction property of Pd-N-TiO₂ thin films was enhanced first and weakened then.The Pd-N-TiO₂ film with 0.48At.%of Pd has the best photocatalytic reduction property.