Study On Composition,structure And Photocatalytic Properties Of C-doped Ti-O Films Prepared By Magnetron Sputtering With Different Carbon Source

Titanium dioxide（Ti O₂）thin film has characteristically excellent chemical stability,low cost,non-toxicity and easy recovery.Also,it has been widely used in the photodegradation of organic pollutants,antibacterial,air purification,dye-sensitized solar cells and other fields.However,pure Ti O₂ has a wide bandgap and considerable recombination of the photo-generated electron-hole pairs,which severely limits its photocatalytic efficiency.One way to overcome this limitation is to alter the bandgap of Ti O₂ through selective doping.In particular,doping of Ti O₂ with C has attracted significant attentions.Because carbon has a large electron-storage capacity,which could absorb the photon-excited electrons to enhance the separation of photo-generated carrier,and doping of Ti O₂ with C can also enhance visible-light absorbance.In the study,C-doped Ti-O films with different titanium suboxide contents are deposited by DC reactive magnetron sputtering at various sputtering powers with CO₂ gas as the only C source and O source.The effect of titanium suboxide contents on the formation of anatase and rutile in the films was investigated during annealing at 600℃in air.In the annealing process,oxygen vacancy defects caused by the lower valence of the titanium in the film can promote the formation of the rutile phase in the films.When the content of Ti⁴⁺in the film is less than 45.4%,it leads to more oxygen vacancy defects and the higher relaxation of the structure,which then promotes the formation of the rutile phase in the samples P140A and P160A.While the content of Ti⁴⁺is higher than 54.8%,namely when the structure relaxation degree is not high enough,the inhibition effect of doped C in the film on rutile phase formation will be profoundly enhanced.Based on the process parameters of C-doped Ti-O films prepared by 120 W DC sputtering with CO₂ as the only carbon source,the addition of C target material as another C source by RF sputring.After annealing treatment,the hybrid structure of rutile and anatase was obtained.The XPS analysis finds that carbon atoms replacing oxygen atoms in Ti O₂ to form Ti-C bond and replacing Ti atoms in Ti O₂ to form Ti-O-C bond.the replaced of Ti position creates a serious distortion of the lattice,making the film’s photocatalytic performance variation.The surface energy component calculation shows that the surface polarity component of the C-doped Ti-O films prepared by the two methods is higher than the dispersion component and the acidic component is higher than the basic component.And annealing can improve the nano-hardness of films.Photocatalytic activity of the thin films is studied by degrading the methyl orange solution under xenon lamp（300 W）irradiation.The result clearly indicates that C doped Ti-O films prepared with CO₂ as carbon source has higher photocatalytic activity than that using CO₂ and C target as C source.