The coral-like carbon nitride array: Rational design for efficient photodegradation of tetracycline under visible light

Abstract

Carbon nitride photoactivity is limited by poor light utilization, rapid recombination of electron-hole (e--h+) pairs, and sluggish surface/interface reaction. Surface/interface modification is a promising strategy to get rid of these restrictions. Therefore, understanding surface/interface properties is highly worth in-depth consideration to improve carbon nitride photoactivity. Herein, the nitrogen-vacancy (Nv) and oxygen substitution (Os) co-modified carbon nitride coral-like array were rationally designed by a combination of thermal calcination and hydrothermal process. Results verified Nv extended the adsorption edge toward visible light and hampered the recombination of e--h+ pairs and Os accelerated surface/interface kinetics. In consequence, the optimized photocatalyst (Nv, Os)-CN-6 can degrade 80 % of tetracycline (TC) with the pseudo-first-order kinetic constant of 0.124 min−1, 13.8-fold higher than pristine carbon nitride. Furthermore, Nv and Os can well resist the toxic effect of interfering agents in simulated practical wastewater. Finally, Nv and Os endow (Nv, Os)-CN-6 mineralizing TC with low/non-ecology-risk intermediates evolution based on the HPLC-MS and T.E.S.T. software simulation. This study provides new insights into the rational design of carbon nitride for photodegrading TC.