Facile synthesis of g-C3N4 nanosheets for effective degradation of organic pollutants via ball milling

Graphitic carbon nitride (g-C3N4) has attracted extensive research interest in pollutants remediation. However, the photocatalytic activity of g-C3N4 was significantly limited by its small specific surface area. In this work, a green, high-energy ball milling method was used to fabricate g-C3N4 nanosheets. The structure, morphology, and optical properties of the prepared g-C3N4 nanosheets were characterized. The effect of ball milling parameters on the photocatalytic performance evaluated by Rhodamine B (RhB) and tetracycline (TC) was investigated systemically. Among the tested samples, the g-C3N4 sample milled with a 4 mL isopropanol solution at a rotation speed of 420 rpm, ball-to-powder weight ratio of 10:1, and milling time of 24 h exhibited the highest RhB degradation efficiency of 91.4% and TC degradation efficiency of 70.2%. The enhanced photocatalytic activity after ball milling was ascribed to the increase in specific surface area and efficient separation of electron-hole pairs. The trapping experiment indicated that holes and superoxide radicals were the main active species in the degradation reaction. Moreover, the photocatalytic degradation mechanism of organic pollutants on g-C3N4 nanosheets was also discussed in detail.