Facile fabrication of g-C3N4/precipitated silica composite with enhanced visible-light photoactivity for the degradation of rhodamine B and Congo red

- The g-C3N4/precipitated silica composite was synthesized via easy preparation.
- The composite displayed enhanced visible light photocatalytic activity.
- The enhancement mechanism was well illustrated.
- The composite presents a potential for dye wastewater treatment.

Novel g-C3N4/precipitated silica (CN/PS) composite with high visible-light activity was successfully synthesized through a facile wetting chemical method. The microstructure, interfacial and optical properties of the obtained CN/PS composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area measurement (BET), UV-visible diffused reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). It is indicated that the tight interfacial interaction was formed between g-C3N4 nanosheets and precipitated silica nanoparticles, which is beneficial for the transfer of electrons and the enhancement of quantum efficiency. The synthesized CN/PS composites exhibited significantly enhanced photoactivity under visible light no matter towards rhodamine B (RhB) or Congo red (CR). Especially for the RhB degradation, the highest rate constant of CN/PS composite was up to around 10 times as much as that of pure g-C3N4. The enhancement mechanism could be mainly attributed to the enhanced adsorption capacity, stronger visible light adsorption as well as the defect or vacancy sites provided by the precipitated silica nanoparticles.

Graphical AbstractThe g-C3N4/precipitated silica photocatalyst was synthesized via easy preparation. Strong interfacial interaction and enhanced charge separation were key factors for the enhancement of the photoactivity of photocatalyst. The photocatalysts exhibited good degradation effect towards dye wastewater under visible light.82