Defect Engineering in g-C₃N₄ Quantum-Dot-Modified TiO₂ Nanofiber: Uncovering Novel Mechanisms for the Degradation of Tetracycline in Coexistence with Cu²⁺

Abstract

Herein, g-C₃N₄ quantum-dot-modified TiO₂ nanofibers were fabricated and used as an efficient photocatalyst for the investigation of the influence of Cu²⁺ and the interaction mechanism between Cu²⁺ and surface defects in tetracycline degradation. Results showed that the effect of Cu²⁺ switched from promoting to inhibiting the tetracycline degradation as the amount of Cu²⁺ accumulated on the catalyst surface increased. The introduction of surface defects can prevent the inhibiting effect of Cu²⁺, resulting in the more complete degradation of tetracycline in contrast to the non-defective sample. Theoretical calculations further revealed that the defects can be used to tune the conduction band of the composite, inducing the reduction reaction of Cu²⁺ and inhibiting the accumulation of Cu on the surface of catalysts. Moreover, the Cu introduced to the catalyst surface provided new active sites, thereby promoting photocatalytic degradation. These findings provide new insights into the design of advanced fiber materials for water purification in complex environments.

Funding

National Natural Science Foundation of China(42177438); Postdoctoral Research Foundation of China(2020M682753); Science and Technology Program of Guangzhou(2019050001); National Key Research and Development Program of China(2019YFE0198000); Pearl River Talent Program(2019QN01L951)