Carbon quantum dot implanted graphite carbon nitride nanorod with enhanced photocatalytic activity: Mechanisms, degradation pathway and DFT calculation

Graphitic carbon nitride (g-C₃N₄) is recognized as a promising photocatalyst for energy and environmental remediation. However, its performance has been limited by issues such as sluggish photocarrier transfer and inadequate light absorption. To address such challenges, we fabricated an innovative photocatalyst by implanting zero-dimensional carbon quantum dots (CQDs) within one-dimensional g-C₃N₄ nanorods. The CQD incorporation accelerated the charge separation/transfer, simultaneously, broadened the light-harvesting ability through the up-converted fluorescent properties. Density functional theory calculations were applied to gain insights into the influence of implanted CQDs on the band gap and charge behavior of CQDs/g-C₃N₄. Moreover, the π-π conjugation between the g-C₃N₄ and CQD enabled the photogeneration of charge carriers. As a result, the CQDs/g-C₃N₄ photocatalyst exhibited superb photocatalytic degradation under visible light irradiation, and the removal rates of tetracycline (TC) was 94.3%, surpassing that of pure g-C₃N₄ by 1.2 times. Additionally, CQDs/g-C₃N₄ processed excellent reusability and mineralization for TC degradation. The photocatalytic degradation pathway of TC was proposed using LC-MS. Mechanisms studies revealed that the photogenerated holes (h⁺), hydroxyl (•OH) and superoxide radicals (•O₂^–) were the primary reactive species responsible for driving the photodegradation process. This study provided a valuable strategy for the design of efficient and stable photocatalysts for antibiotic wastewater remediation.