In-situ covalent bonding of carbon dots on two-dimensional tungsten disulfide interfaces for effective monitoring and remediation of chlortetracycline residue

In view of the increasing threat of chlortetracycline (CTC) in water to human health and the ecological environment, how to detect and remove CTC in wastewater simply and effectively remains an important and challenging task. Herein, a multifunctional platform for the simultaneous detection and degradation of CTC is developed by in-situ synthesis of carbon dots (CDs) in the two-dimensional (2D) WS2 interface by covalent bonding. The as-prepared 2D WS2/CDs nanocomposites can not only be used as an intelligent fluorescence probe for CTC detection with good sensitivity (LOD = 7.5 nM) and selectivity but also has good photodegradation ability for CTC (degradation efficiency attained 85.58%). Moreover, the possible mechanisms for the detection and photodegradation of CTC by 2D WS2/CDs were also investigated by theoretical calculations, time-resolved fluorescence decay curves, and electron spin resonance (ESR) analyses. The exceptional photoelectric properties of 2D WS2/CDs are ascribed to the CDs bound onto the 2D WS2 interface by covalent bonding forming heterojunctions, which effectively promote strong interfacial interactions between CDs and 2D WS2, thereby providing more effective charge transfer and enhancing the detection efficiency and photocatalytic activity. In addition, the possible degradation pathway for CTC was speculated via identification of intermediates and frontier electron density calculation. Overall, this study not only proves that the 2D WS2/CDs nanocomposites have great potential for the simultaneous detection and degradation of CTC in aquatic environments but also provides a novel idea for the efficient and stable design of multifunctional nanomaterials for environmental pollution monitoring and purification, which is of great significance to both practical applications and basic research.