Magnetic-room temperature phosphorescent multifunctional nanocomposites as chemosensor for detection and photo-driven enzyme mimetics for degradation of 2,4,6-trinitrotoluene

Abstract

In recent decades, considerable efforts related to the study of 2,4,6-trinitrotoluene (TNT) have been focused on either developing ultraselective and ultrasensitive methods for real-time analytical detection or exploiting highly efficient and green technologies for treatment of contaminated waters. In the present work, combining the magnetic response property of Fe₃O₄ nanoparticles with the chemosensory property of quantum dots (QDs), Fe₃O₄ magnetic nanoparticles and Mn-doped ZnS QD nanocomposites (MNPs/QD NCs) have been synthesized and used for room-temperature phosphorescence (RTP) sensing and magnetic separation of captured ultratrace TNT in water. Notably, magnetic-RTP MNPs/QD NCs were found as photo-driven enzyme mimetics for degradation of TNT through Haber–Weiss cycle reactions for the first time. Meanwhile, MNPs/QD NCs exhibited a highly selective response for TNT with detection limit down to 12.5 nM through the quenching of ⁴T₁–⁶A₁ transition emission. By in situ monitoring electron paramagnetic resonance (EPR) signals, production of hydroxyl radical (OH˙) is attributed fundamentally to the catalytic reactions occurring at metal ions on the surface of Fe₃O₄ nanoparticles rather than those released from the MNPs into a solution. The proposed methods, as well as being suitable for detecting ultratrace TNT and distinguishing different nitro-compounds, could be used as one of the most promising approaches for developing highly efficient degradation of organics contaminated waters to generate treated waters which could be easily reused or released into the environment without any harmful effects.