Manipulating Active Sites of 2D Metal–Organic Framework Nanosheets with Fluorescent Materials for Enhanced Colorimetric and Fluorescent Ammonia Sensing

Abstract

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 ...

In situ encapsulation of ZrQ in UiO‐66 (Zr‐BDC) for pore size control to enhance detection of a nerve agent simulant dimethyl methyl phosphonate

“…The primary challenge with the fluorescent sensors using 8‐Q is the poor stability of metal/8‐Q compounds including ZnQ and AlQ. [ 12,57 ] The degradation of ZrQ can also be observed in Figure S5. The crystalline framework appears intact after sensing experiments, so the optical color change of the ZrQ@Zr‐BDC composite is likely from encapsulated ZrQ.…”

“…[8] Metal organic frameworks (MOFs) have shown promise for numerous sensing applications. [9][10][11][12] Fluorescent sensors have been synthesized using Zr, 4,4 0stilbenedicarboxylic acid and Eosin Y for nitroaromatics sensing. [13] Zr-BDC, also known as UiO-66, have been used for DMMP detection and even degradation.…”

Metal–organic frameworks for NH3 adsorption by different NH3 operating pressures

“…Colorimetric NH 3 sensors are advantageous in real‐time visual analyte detection 57–59 . Introduction of luminescent inorganic complexes or organic linkers could allow MOFs to perform colorimetric sensing of NH 3 .…”

Electrochemical performance of asymmetric device using the nickel–zinc organometallic structure

“…[36,[39][40][41][42] In addition, the peaks at approximately 10.3 and 12.6 are attributed to the (111) and ( 200) planes of the Zn MOF. [40,[42][43][44] Other diffraction peaks are the overlap of Ni and Zn MOFs. Figure 2 shows the FTIR spectra of NZMOF/CC.…”