Layered double hydroxides as efficient photocatalysts for visible-light degradation of Rhodamine B.

A series of Zn/M-NO3-LDHs (M=Al, Fe, Ti, and Fe/Ti) have been synthesized by two different methods, and their activities for visible-light photocatalytic degradation on Rhodamine B (RB) were tested. Solids were analyzed by XRD, FT-IR, and ICP characterization, confirming the formation of pure LDH phase with good crystal structure. It was observed that the band gap of these nitrate LDH materials was following this order: Zn/Fe-NO3-LDHs (2.55 eV)>Zn/Fe/Ti-NO3-LDHs (2.88 eV)>Zn/Ti-NO3-LDHs (3.0 3eV)>Zn/Al-NO3-LDHs (3.23 eV); however, the degradation performance of RB by four materials followed the order: Zn/Ti-NO3-LDHs (98%)>Zn/Al-NO3-LDHs (96%)>Zn/Fe/Ti-NO3-LDHs (88%)>Zn/Fe-NO3-LDHs (72%). In addition, a possible mechanism for photocatalytic degradation on RB has also been presumed. Moreover, after three regeneration cycles, the percentage of RB degradation rate was still close to 90%.