Ti-based layered double hydroxides: Efficient photocatalysts for azo dyes degradation under visible light

Three types of Ti-based Layered Double Hydroxides (Zn/Ti-NO3-LDHs with Ti element on LDH sheet, Zn/Al-Ti/Schiff-base-LDHs with Ti element in LDH interlayer and CeO2/ZnTi-LDH composite containing TiO2) were synthesized by different environmental friendly methods. Their activities of photocatalytic degradation of Methyl orange and Methylene blue under visible light were tested. Ti-based LDHs were characterized by XRD, FT-IR, BET and ICP-AES, confirming the formation of pure LDH phase with good crystal structure. The as-synthesized Ti-based LDH materials showed the narrow band gap (all smaller than 3.0 eV) and high removal efficiency for Methyl orange and Methylene blue under visible light, and the decomposition performance of these dyes decreased in the order of CeO2/ZnTi-LDH composite > Zn/Al-Ti/Schiff-base-LDHs>Zn/Ti-NO3-LDHs. In addition, the kinetics and possible mechanisms for photocatalytic degradation on Methyl orange and Methylene blue were also discussed in details. Moreover, the thermal regeneration for re-use of Zn/Al-Ti/SB-LDHs after photoreaction was feasible for at least three cycles (degradation amount still over 85%). (C) 2013 Elsevier B.V. All rights reserved.