Synergistically enhanced peroxidase-like activity of Fe3O4/Ti3C2 MXene quantum dots and its application in colorimetric determination of Cr (VI)

The rational design of artificial nanozymes has become a research focus owing to its low cost and high sensitivity. Herein, we present a facile ultrasonic strategy for the preparation of Fe3O4@MXene quantum dots (Fe3O4@MQDs) hybrid material, showing an enhanced peroxidase-like activity relative to pure MQDs and Fe3O4 magnetic nanoparticles (MNPs). The catalytic mechanism of the Fe3O4@MQDs is studied by steady-state fluo-rometric analysis, revealing that Fe3O4@MQDs can effectively decompose H2O2 to produce reactive hydroxyl radicals (center dot OH). Furthermore, density functional theory calculations demonstrate that the dramatic catalytic activity of Fe3O4@MQDs derives from the active sites of interfacial Fe-Ti dimer, which can significantly activate the absorbed H2O2 and promote its decomposition into center dot OH. Accordingly, a sensitive colorimetric sensor is proposed to detect Cr (VI), displaying a low detection limit of 0.26 mu M. This work opens up a new approach for the design and synthesis of MQDs-based peroxidase-like enzymes and demonstrates its great potential in the detection of environmental pollutants.