A reduction-oxidation strategy modulated fluorescence of MXene quantum dots for ultrasensitive Fe3+ sensing

The escalating threat of heavy metal pollution to both environmental integrity and public health underscores the urgent need to develop accessible, and highly efficient analytical methods. In this study, we propose a facile reduction-oxidation strategy for fabricating MXene quantum dots (r-MQDs) with high sensitivity toward Fe 3+ detection. The synthesis process involves the oxidative cleavage of MXene via H 2 O 2 -assisted hydrothermal treatment to yield quantum dots, followed by chemical reduction with NaBH 4 . The r-MQDs exhibit excellent fluorescence quantum yields, attributed to both strong quantum confinement effects and reduced non-radiative losses. Fe 3+ efficiently suppresses the fluorescence of r-MQDs through a cooperative mechanism where static quenching and the inner filter effect operate in tandem. The fluorescent probe exhibits a linear response to Fe 3+ in the range of 0.8 - 1.0 mM, along with a notably low detection limit of 5 nM. This study elucidates the selectivity mechanism of MQDs as fluorescent probes for metal ions and broadens the application prospects of MXene-based quantum dots for sensing.