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

• Zn/M–NO3-LDHs (Al, Fe, Ti, and Fe/Ti) have been synthesized.
• The band gap of LDH materials followed the order: Zn/Fe > Zn/Fe/Ti > Zn/Ti > Zn/Al.
• The photocatalytic performance by four materials: Zn/Ti > Zn/Al > Zn/Fe/Ti > Zn/Fe.
• The mechanism for photocatalytic degradation on Rhodamine B has also been presumed.
• Zn/Ti–NO3-LDHs after RB degradation were feasible at least three cycles.

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 (3.03 eV) > 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%.

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