Photocatalytic Degradation of Rhodamine B over Pb3Nb4O13/Fumed SiO2 Composite under Visible Light Irradiation

Novel Pb 3 Nb 4 O 13 /fumed SiO 2 composite photocatalysts were prepared by a deposition−precipitation method for rhodamine B (RhB) photodegradation under visible light irradiation. Techniques such as XRD, UV−vis reflectance spectroscopy, and SEM were adopted to explore the characteristics of samples. Compared to the unsupported Pb 3 Nb 4 O 13 sample, the composite photocatalysts showed notably improved photocatalytic activities for RhB degradation as the result of significantly strengthened interaction between the dye molecules and the Pb 3 Nb 4 O 13 active component. The kinetic analysis demonstrated that rhodamine (the completely de-ethylated product of RhB) can be more easily degraded than RhB, and thus, the N -de-ethylation process is the rate-limited step of RhB photodegradation over Pb 3 Nb 4 O 13 /fumed SiO 2 composites. It was proposed that there could be three different reaction routes for RhB photodegradation over the Pb 3 Nb 4 O 13 /fumed SiO 2 composite materials, including the direct degradative oxidation of RhB in solution bulk (and/or on samples surface), and two routes initiated by surface N -de-ethylation reactions.