A novel morphological conversion strategy of carbon nitride by ammonia water to enhance the photocatalytic inactivation of Escherichia coli

Abstract

Carbon nitride-based nanomaterials are widely used in photocatalytic degradation. However, the common type has limited performance, and the traditional functionalization procedure is fussy. Herein, a morphological conversion strategy based on ammonia water is proposed for the carbon nitride-based nanomaterials (C3N4) to improve the photocatalytic performance. Under the effect of ammonia water, C3N4 is capable of conversing into hollow tube (C3N4 HTs) and hollow cone (C3N4 HCs). Further assay results demonstrate that the transformed morphology can increase the specific surface area, particularly for C3N4 HCs, generating more exposed active sites. The conduction band (ECB) and valence band (EVB) of the C3N4 HCs are −1.05 (±0.005) V and 1.69 (±0.015) V, respectively, which are significantly higher than those of the common g-C3N4 and C3N4 HTs, suggesting stronger photocatalytic properties. Meanwhile, the produced reactive oxygen species (ROS) from the C3N4 HCs are polybasic, which the level order is •O2–＞•OH＞1O2. Subsequently, C3N4 HCs were employed to degrade Escherichia coli in the water. Exposing in xenon lamp, the generated free radicals and 1O2 from C3N4 HCs rapid oxidize and eliminate the Escherichia coli, and the purification rate reaches ∼ 100 % within 2 h. In contrast to other commonly used methods for photocatalytic degradation, this work focuses on material morphology conversion to propose a robust and highly efficient method for performance improvement. It has promising applications in water purification and ecological protection.