Abstract:

Cr-doped TiO₂ nanoparticles were synthesized by one-step flame spray pyrolysis technique. The effects of Cr³⁺ doping on the microstructure, light absorption property, and photocatalytic activity of the samples were investigated. It is found that increasing Cr³⁺ concentration restrains the formation of anatase and simultaneously favors the formation of rutile. At low concentration (≤1%), Cr is mainly incorporated into the crystal lattice of TiO₂ in the form of Cr³⁺, while high Cr concentration promotes the formation of Cr₂O₃ clusters. The result of photocatalytic degradation of 2,4-dichlorophenol demonstrates that appropriate Cr³⁺ doping can evidently enhance the visible-light photocatalytic activity of TiO₂. The optimal Cr3+ concentration to obtain the highest photocatalytic activity is 1at%. The improvement of visible-light photocatalytic activity derived from Cr doping is mainly related to the enhancement of visible light absorption, appropriate crystalline composition, and improved transfer efficiency of photogenerated electrons and holes.

Key words: flame spray pyrolysis, titanium dioxide, Cr doping, photocatalytic activity