Synthesis of metal-free functionalized g-C3N4 nanosheets for enhanced photocatalytic activity

A new visible-light active polymeric semiconductor was fabricated covalently functionalizing the g-C3N4 using halogenated phenyl groups. 4-bromobenzonitrile was employed to introduce organic motifs into g-C3N4 networks through a convenient one-pot thermally induced process. The functionalization of the g-C3N4 with the halogenated phenyl group extended the original π-conjugation system, leading to the enhancement of visible-light absorption, and the separation of charge carriers. Introducing the new group, the g-C3N4 pore structure was enriched, resulting in a larger specific surface area and an increase in active sites. The functionalization led to an easier exfoliation of the g-C3N4 framework into thinner layers, enhancing its dispersion ability in the water. Under visible-light irradiation, the as-prepared semiconductor exhibited increased photocatalytic activity to the pristine g-C3N4. The photocatalytic performances were investigated on a simple organic compound, methanol, a model dye, rhodamine B, and an emergent contaminant, 4-nitrophenol. This research provided new insights on metal-free modified g-C3N4 as a visible-light photocatalyst.