Facile fabrication of metal-free urchin-like g-C₃N₄ with superior photocatalytic activity

Spherical urchin-like graphitic carbon nitride nanoparticles with high specific surface area were prepared by thermal-induced self-condensation of melamine and a flower-like porous silica template. These urchin-like g-C₃N₄ were characterized by TEM, N₂ physical adsorption, XRD, FT-IR, XPS, UV-Vis and PL spectra. After complete removal of the silica template, the urchin-like g-C₃N₄ particles exhibited almost 12.3 times higher activity than the conventional bulk g-C₃N₄ during photocatalytic degradation of RhB under visible light irradiation. The enhanced photocatalytic activity can be attributed to the increased surface area (S_BET = 131.5 m² g^-1) together with the reduced recombination of photogenerated electron-hole pairs, as confirmed by the PL spectra. These urchin-like g-C₃N₄ nanoparticles demonstrate semiconductor-redox functions that make them candidates for use as catalyst supports, nitrogen-rich templates, and selective organic synthesis photocatalysts.