Synthesis of C–Cl-codoped titania/attapulgite composites with enhanced visible-light photocatalytic activity

We demonstrate the synthesis of C–Cl-codoped titania/attapulgite (TiO2/ATT) composites containing a mixture of TiO2 phases by a facile sol-gel method at 70 °C using titanium tetraisopropoxide as the TiO2 precursor and ATT as a support for the TiO2 nanoparticles. The photocatalytic activity of the C–Cl-codoped TiO2/ATT composites with mixed anatase/brookite/rutile phases obtained at pH = 3.0 was much higher than that of commercially available Degussa P25 for the photocatalytic degradation of acid red G under visible-light irradiation. The excellent photocatalytic activity of the developed composite originates from the nonmetal codoping, which extends the absorption edge of TiO2 into visible region, and the presence of multiple phases, which slow the recombination of photoexcited electron/hole pairs. The formation of hydroxyl radicals during the photocatalytic degradation process was detected by photoluminescence probing using terephthalic acid. A mechanism for photocatalysis over the C–Cl-codoped TiO2/ATT composites was proposed.