A Eu-MOF/EDTA-NiAl-CLDH fluorescent micromotor for sensing and removal of Fe3+ from water
This paper reports a novel bioinspired Pt-free three-dimensional (3D) EDTA (Ethylene Diamine Tetraacetic Acid)-functionalized Eu-MOF (Metal Organic Framework)-based fluorescent micromotor as an active self-propelled micromachine for detection, capturing, and removal of Fe3+ from water. This micromotor was composed of EDTA-NiAl-CLDHs (calcined layered double hydroxides)/MnO2 and a Eu-MOF, with each component functioning differently. The outer fluorescent Eu-MOF layer acted as a fluorescent sensor for detecting Fe3+, while the inner EDTA-functionalized NiAl-CLDH/MnO2 layer functioned as a functional unit for Fe3+ adsorption, as well as the buffer layer for the nucleation and growth of the Eu-MOF. MnO2 served as a catalyst in decomposing H2O2 for self-propulsion of the micromotor. The obtained micromotor exhibited a circle motion form with an average speed of 56.9 μm s−1 in 5 wt% H2O2. This EDTA-functionalized Eu-MOF-based fluorescent micromotor showed excellent selectivity, high sensitivity (Stern–Volmer constant Ksv = 1.3 × 104 L mol−1, and limit of detection LOD = 0.15 μM) and high adsorption capacity (the maximum equilibrium adsorption capacity qmax = 112 mg g−1) for Fe3+. Therefore, the novel 3D bifunctional fluorescent micromotor combining the MOF, EDTA-functionalized CLDHs and autonomous motion is promising for the simultaneous detection/adsorption and removal of pollutants, expanding the potential resources for micromotors and providing an efficient option for water quality monitoring and wastewater treatment.