MXene Quantum Dot-Modified\nFlower-Like FeOOH for Dual-Mode\nNitrite Sensing

Nowadays, the rational design of\nhigh-performance simulated\nnanozymes\napplied to environmental detection has become a current research hotspot.\nHerein, we employ a urea/ethanol solution synergistic-mediated approach\nto prepare MQDs@FeOOH nanozymes with significant peroxidase activity.\nThe steady-state fluorescence analysis and density-functional theory\ncalculations (DFT) investigated that the MQDs@FeOOH nanozymes possess\nremarkable catalytic activity. This is attributed to the active sites\nof the Fe-Ti dimer, which effectively adsorb H<sub>2</sub>O<sub>2</sub> and activate its decomposition into reactive •OH. We have\ndeveloped a dual-mode assay combining colorimetric and electrochemical\nmethods for the determination of nitrite in the environment. The detection\nlimits are 1.58 and 2.99 μM, achieving a facile determination\nin the range of 50–300 μM. It also demonstrates the advantages\nof high sensitivity, anti-interference, and reliability. This work\nprovides an idea for the preparation of nanomaterials with high-performance\nperoxidase activity and demonstrates their wide application in environmental\nmonitoring.