Onion-like carbon modified porous graphitic carbon nitride with excellent photocatalytic activities under visible light

A series of onion-like carbon modified porous g-C₃N₄ (OLC/pg-C₃N₄) composites have been fabricated by a simple ultrasonic adsorption approach. The resultant OLC/pg-C₃N₄ composites exhibit excellent photocatalytic activity and stability towards the degradation of the dyes and phenol in aqueous solution under visible-light irradiation. The composite with 2.0 wt% OLC content shows the optimal photocatalytic activity for degrading rhodamine B (RhB), its rate constant is about three times that of pure pg-C₃N₄. The improved photocatalytic activity is mainly attributed to the synergetic effect of pg-C₃N₄ and OLC, including larger surface area, stronger visible light adsorption and efficient separation of photogenerated electrons and holes. Moreover, a possible mechanism of photocatalytic reaction over OLC/pg-C₃N₄ composite is proposed.