Photocatalytic degradation of rhodamine B over Pb3Nb4O13/fumed SiO2 composite under visible light irradiation

Novel Pb3Nb4O13/fumed SiO2 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 Pb3Nb4O13 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 Pb3Nb4O13 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 Pb3Nb4O13/fumed SiO2 composites. It was proposed that there could be three different reaction routes for RhB photodegradation over the Pb3Nb4O13/fumed SiO2 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.