Cellulose nanofibrils anchored Ag on graphitic carbon nitride for efficient photocatalysis under visible light

Abstract

Although polymeric graphitic carbon nitride (CN) is considered an appealing metal-free photocatalyst for energy conversion and environmental remediation, its application still faces challenges owing to its limited photocatalytic activity under visible light irradiation. Herein, we prepared an efficient doped CN photocatalyst using sustainable cellulose nanofibrils (CNFs) to anchor Ag onto CN. The carbon originating from CNFs was doped successfully, which in consequence enhanced the visible light absorption of CN significantly. Furthermore, the carboxyls and hydroxyls exposed on the CNF surface, as well as the intrinsic entangled network of CNFs, provided more Ag chemically and physically anchored on the resultant CN framework. The Ag amount of Ag/CCN-4 (doped with CNF and 0.04 g of AgNO₃) increased significantly, which was about 2 times higher than that of Ag/CN (doped with only AgNO₃), and the band gap was narrowed to 2.30 eV. As a result, rhodamine B (RhB) and tetracycline (TC) were efficiently degraded under visible light, and the photodegradation rate constant of RhB reached 0.12695 min⁻¹, whereas that of Ag/CN and CN was 0.06956 and 0.04892 min⁻¹, respectively. The possible mechanism was summarized. Benefiting from the relatively higher specific surface area, carbon doping and Ag anchoring, Ag/CCN-4 exhibited excellent photocatalytic activity, and this work provides a simple and efficient strategy for fabricating high-performance CN photocatalysts for the removal of pollutants.