g-C3N4/SiO2–HNb3O8 composites with enhanced photocatalytic activities for rhodamine B degradation under visible light

Visible light-responsive g-C3N4/SiO2–HNb3O8 composite photocatalysts were prepared by a solid state-reaction method with melamine as a g-C3N4 precursor. The photocatalytic activities of the samples were evaluated for rhodamine B (RhB) degradation under visible light irradiation and the results were compared with those obtained over pure SiO2–HNb3O8 and g-C3N4. Techniques such as XRD, FT-IR, SEM, TEM, and UV–vis diffuse reflectance spectroscopy were adopted to explore the characteristics of samples. The g-C3N4/SiO2–HNb3O8 composite materials exhibited superior activities than pure SiO2–HNb3O8 and g-C3N4; the sample prepared with SiO2–HNb3O8 to melamine ratio being 1:2 and the heating duration being 4 h performed the best. The improved activity of g-C3N4/SiO2–HNb3O8 is attributed to the unique synergetic effect between SiO2–HNb3O8 and g-C3N4.

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► g-C3N4/SiO2–HNb3O8 composites were prepared by solid state reaction.
► g-C3N4/SiO2–HNb3O8 composites are visible light active photocatalysts.
► g-C3N4/SiO2–HNb3O8 exhibited superior activity than SiO2–HNb3O8 and g-C3N4.
► The enhanced activity is ascribed to the synergism between the two components.