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 Fe 3 O 4 @MXene quantum dots (Fe 3 O 4 @MQDs) hybrid material, showing an enhanced peroxidase-like activity relative to pure MQDs and Fe 3 O 4 magnetic nanoparticles (MNPs). The catalytic mechanism of the Fe 3 O 4 @MQDs is studied by steady-state fluorometric analysis, revealing that Fe 3 O 4 @MQDs can effectively decompose H 2 O 2 to produce reactive hydroxyl radicals (•OH). Furthermore, density functional theory calculations demonstrate that the dramatic catalytic activity of Fe 3 O 4 @MQDs derives from the active sites of interfacial Fe-Ti dimer, which can significantly activate the absorbed H 2 O 2 and promote its decomposition into •OH. Accordingly, a sensitive colorimetric sensor is proposed to detect Cr (VI), displaying a low detection limit of 0.26 μM. 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. • A novel Fe 3 O 4 @MQDs heterostructure was synthesized. • Peroxidase-like activity of Fe 3 O 4 @MQDs was significantly enhanced. • Experiment and DFT calculations revealed the possible reaction mechanism. • Colorimetric detection of Cr (VI) with a detection limit of 0.26 μM in the range from 0 to 60 μM.