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2-chloroethyl ethyl sulfide (CEES) is a simulant for the chemical warfare agent, bis(2-chloroethyl) sulfide, also known as mustard gas. Here, we demonstrate a facile and rapid method to synthesize a...

features give MOFs great potential in different applications, such as gas storage, separation, catalysis, and sensors. [4][5][6] Many studies have investigated the design of bulk MOFs. Recently, the preparation of nanoscale MOF crystals with controlled size, shape, and morphology has become an important area of research because conventional methods for bulk MOFs synthesis do not meet desired requirements for many applications. [7,8] Nanoscale MOFs provide a higher specific surface area than bulk MOFs, resulting in performance enhancement in various applications such as gas storage, separation, catalysis, and sensing. [7,9,10] Thus, the synthesis and functionalization of nanoscale MOFs are crucial for achieving specific goals in various applications.Recently, 2D nanomaterials have received increasing research interest due to their unique properties when compared to other types of nanomaterials including, 0D nanoparticles, 1D nanowires, or 3D nano networks. [11] The exceptional properties of 2D nanomaterials include charge transport, large field-effect, and unique light-matter interaction modalities, which have promises in addressing present challenges in healthcare, energy conversion, storage, and electronics. [12] These exclusive properties have inspired the synthesis of 2D MOFs nanosheets. [13] Two methods have been used so far, the top-down and the bottom-up method. The chemical tunability of MOFs from bottom-up approach yields good results, especially for sensors. [14] Active sites on the surface of 2D MOFs are highly accessible, even more than their pores or channels, which allow more interactions that enhance the performance in gas sensing, catalysis, and separation applications. [15] Furthermore, the ultra-thin nature of 2D MOFs allows for rapid mass and electron transfer for chemical sensors. [16] Therefore, manipulating the surface-active sites of 2D MOFs can be exploited to enhance the performance of selective chemical sensing.Ammonia is a hazardous gas commonly produced in chemical manufacturing, petroleum refining, pesticide production, fertilizer factories, textile factories, refrigeration systems, food processing plants, livestock buildings, and many other industries. [17] It also occurs naturally during the decomposition of 2D metal-organic frameworks (MOFs) offer high surface area and unique accessibility to active adsorption sites making them appealing for gas sensing applications. 2D MOFs-based sensors are gaining traction for detecting hazardous flu-gases such as ammonia selectively at low concentrations. Fluorescent and colorimetric sensing are promising techniques offering high sensitivity, selectivity, and rapid response in simple applications. In this work, Zn-BTC is synthesized as 2D-MOFs nanosheet with approximate thickness of 2.52 nm via a fast, facile, direct synthesis technique. The introduction of 8-hydroxyquinoline during synthesis forms fluorescent compounds with zinc (ZnQ) which is encapsulated and decorated onto Zn-BTC. Inherent charges on ZnQ lead to the agglomeration of multiple ...

Metal−organic frameworks (MOFs) present specific adsorption sites with varying electron affinity which are uniquely conducive to selective gas sensing but are typically large-band-gap insulators. On the contrary, multiwall carbon nanotubes (MWCNTs) exhibit superior mesoscopic transport exploiting strong electron correlations among sub-bands below and above the Fermi level at room temperature. We synergize them in a new class of nanocomposites based on zeolitic imidazolate framework-8 (ZIF-8) and report selective sensing of CH 4 in ∼10 parts-per-billion (ppb) with a determined limit of detection of ∼0.22 ppb, hitherto unprecedented. The observed selectivity to CH 4 over non-polar CO 2 , polar volatile organic compounds, and moisture has roots in competing electron-sharing mechanisms at its different adsorption sites. This important result provides a significant reference to guide future MOF-related composite research to achieve the best sensing performance. On molecular adsorption, MWCNTs facilitate electrical transport via manipulating the ZIF-8 band gap to show a p-type semiconductor behavior with lower activation energy to induce a measurable resistance change. Excellent repeatability and reversibility are shown. A carbon-engineered MOF composite has the potential to actuate similar selective response to low reactive gases via carrier manipulation in the energy band gap.