Constructing carbon-vacancy introduced g-C3N4 coating ZIF-8 with strong adsorption performance and internal electric field for enhanced photodegradation

Abstract

Graphitic carbon nitride (g-C3N4) is limited in photocatalytic degradation efficiency owing to its weak adsorption capacity and finite charge utilization. In this work, carbon-vacancy defective g-C3N4 (CNP) wrapped around Zeolitic-imidazolate-framework-8 (ZIF-8) photocatalysts (ZCNP) were designed to overcome these drawbacks. ZCNP exhibits strong antibiotic adsorption effect due to π-π interactions and intermolecular forces. Benefitting from abundant carbon-vacancy coordination sites on CNP, ZIF-8 tightly binds to CNP, forming a built-in electric field at the contact interface and efficiently promoting electron-hole separation. Considering the strong adsorption performance combined with efficient electron-hole separation, ZCNP illustrates superhigh photolytic antibiotic activity (6.2 times higher than that of the pristine g-C3N4, 5.0 times higher than that of pure ZIF-8) and can degrade 98 % Doxycycline, 98 % Tetracycline and 61 % Ofloxacin within 30 min. ZCNP also maintains good efficiency in surface water and ground water. Moreover, the radical trapping experiments demonstrate that h+, 1O2 and •O2− have significant effects on the photocatalytic process, while h+ and 1O2 have great effects on the adsorption process. This work will provide novel insights for the design and development of efficient hybrid photocatalysts with high absorption capacity and photolytic activity.