Cysteine‐Functionalized Ti ₃ C ₂ MXene Quantum Dots as Fluorescent Sensors for the Detection of Ag ⁺

Abstract MXene quantum dots (MQDs), an emerging zero‐dimensional nanomaterial, have garnered significant attention from researchers due to their distinctive physical and chemical properties. In this study, cysteine‐functionalized Ti 3 C 2 MQDs were synthesized using a facile hydrothermal methods, resulting in the functionalized Ti 3 C 2 MQDs exhibiting intense blue fluorescence attributed to size‐dependent effects and surface defects. Furthermore, the cysteine‐functionalized Ti 3 C 2 MQDs exhibit excitation wavelength‐dependent emission behavior and serve as a highly sensitive fluorescent probe for Ag + detection with an impressive low limit of detection (LOD) of 0.015 μM. Moreover, they demonstrate exceptional sensitivity and selectivity in determining Ag + . This study presents a novel approach for the detection of Ag + and highlights the immense potential of cysteine‐functionalized Ti 3 C 2 MQDs in environmental applications.