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Rapid and Scalable Synthesis of Zeolitic Imidazole Framework (ZIF‐8) and its Use for the Detection of Trace Levels of Nitroaromatic Explosives

A facile and inexpensive approach for scalable synthesis of highly porous zeolite imidazolate framework nanoparticles (ZIF‐8) is described. The synthesis, done in an aqueous solution at room temperature, takes just 2 min compared to hours or days in nonaqueous conditions. The structural integrity and phase purity of ZIF‐8 are studied through X‐ray powder diffraction and are of sodalite topology, and its surface nature and composition are determined with X‐ray photoelectron spectroscopy. ZIF‐8 has high crystallinity, large Brunauer–Emmett–Teller surface area (1398.7 m2 g−1) and pore volume (0.62 cm3 g−1). Images of ZIF‐8 show hexagonal nanocrystals, whose growth is observed with atomic force microscopy (AFM). Thermogravimetric analysis data testify the thermal stability of the material (490 °C in air). Zeta potential measurement confirms that trinitrotoluene (TNT) molecules adsorb onto ZIF‐8. The interaction between the electron‐deficient aromatic core of TNT and the electron‐rich ZIF‐8 is considered to favor the formation of donor–acceptor electron‐transfer mechanism, and the electron conductivity of ZIF‐8 facilitates the effective reduction of TNT. Using the prepared ZIF‐8, an electrochemical sensor is fabricated to detect TNT and other nitroaromatic explosives in aqueous phase. The sensor performance is highly linear, with very low limit of detection (346 × 10−12m), and is unaffected by the presence of various interferents.