Pyrolytic synthesis of organosilane-functionalized carbon nanoparticles for enhanced photocatalytic degradation of methylene blue under visible light irradiation

The use of carbon-based nanomaterials as effective photocatalysts is an ideal alternative for environmental remediation. Here, (3-aminopropyl)triethoxysilane-functionalized carbon nanoparticles (SiCNPs) were prepared using a simple pyrolysis method with sodium citrate and urea as the precursors. The samples were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and photo-electrochemical measures. The obtained SiCNPs-2.0 showed a better visible light response and more effective photocatalytic activity for degradation of methylene blue (MB) compared with pure CNPs. Under visible light irradiation, 98.8% of the MB was decomposed within 75 min when SiCNPs-2.0 was used as the photocatalyst. The high photocatalytic activities of SiCNPs-2.0 could be attributed to enhanced light absorption in the visible region, and improved photogenerated electron-hole separation efficiency. A possible photocatalytic mechanism for removal of MB over SiCNPs-2.0 was proposed based on active species trapping experiments. Recycling experiments showed that SiCNPs-2.0 had good stability during photocatalysis. This work provides a new easy method to synthesize carbon-based nanomaterials and to catalytically degrade organic pollutants in water under visible light irradiation.