Salt-templated synthesis of 3D porous foam-like C3N4towards high-performance photodegradation of tetracyclines

Photocatalysis has emerged as an efficient method to treat highly noxious and persistent antibiotics such as tetracyclines (TCs) in the ecological environment. Carbon nitride (C3N4) is one promising photocatalyst, but the synthesis of C(3)N(4)with a tunable chemical structure, extended visible-light harvesting, and strong photoactivity remains a challenge. Herein, 3D porous foam-like C3N4(F-C3N4) was facilely prepared by thermal polycondensation of melamine with salt templates. F-C(3)N(4)bears a hierarchically porous structure with a moderate specific surface area of 50.3 m(2)g(-1), which is 12 times higher than that of bulk C3N4. Besides, F-C(3)N(4)shows a shorter average lifetime of photoexcited charge carriers and a stronger photocurrent response than bulk C3N4, since the hierarchical pores and functional groups of F-C(3)N(4)promote the migration of photoinduced charge carriers. The high photocatalytic activity of F-C(3)N(4)is displayed in the degradation of TC, for which the kinetic constant is 64 times higher than that of bulk C3N4. Finally, the photodegradation mechanism of TC is revealed by detecting reactive oxygen species such as OH,(1)O(2)and O(2)(-)through electron paramagnetic resonance, as well as analyzing the intermediate degradation products of TC. This work provides a facile method to prepare porous C(3)N(4)with a remarkably enhanced photocatalytic activity.