Visible-light Photocataltic Activity of Cr-doped TiO2 Nanoparticles Synthesized by Flame Spray Pyrolysis

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 ( %), 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.