Facile Conversion of Hydroxy Double Salts to Metal–Organic Frameworks Using Metal Oxide Particles and Atomic Layer Deposition Thin-Film Templates

Abstract

Rapid room-temperature synthesis of metal-organic frameworks (MOFs) is highly desired for industrial implementation and commercialization. Here we find that a (Zn,Cu) hydroxy double salt (HDS) intermediate formed in situ from ZnO particles or thin films enables rapid growth (<1 min) of HKUST-1 (Cu3(BTC)2) at room temperature. The space-time-yield reaches >3 × 10(4) kg·m(-3)·d(-1), at least 1 order of magnitude greater than any prior report. The high anion exchange rate of (Zn,Cu) hydroxy nitrate HDS drives the ultrafast MOF formation. Similarly, we obtained Cu-BDC, ZIF-8, and IRMOF-3 structures from HDSs, demonstrating synthetic generality. Using ZnO thin films deposited via atomic layer deposition, MOF patterns are obtained on pre-patterned surfaces, and dense HKUST-1 coatings are grown onto various form factors, including polymer spheres, silicon wafers, and fibers. Breakthrough tests show that the MOF-functionalized fibers have high adsorption capacity for toxic gases. This rapid synthesis route is also promising for new MOF-based composite materials and applications.

Template synthesis of hierarchical porous metal–organic frameworks with tunable porosity

“…most likely because of dehydration and rehydration. 41 In addition, broader XRD peaks are observed in the patterns of CuBTC_An than those in the patterns of C-Cu-BTC and the simulation result, which can be attributed to either the small crystallite size or abundance of lattice defects. 42,43 These crystal structures were further studied using FTIR spectroscopy.…”

In Situ Time-Resolved Attenuated Total Reflectance Infrared Spectroscopy for Probing Metal–Organic Framework Thin Film Growth

“…These two peaks are associated with vibrations of the ${\text{NO}}_3^{-}$ groups mainly present in the (Zn, Cu) hydroxy nitrate double salt. 33 The integrated peak area for $vfalse({\text{NO}}_3^{-}false)$ at ≈ 1420 cm −1 (Figure 2b) increases dramatically and reaches saturation after 1 min, indicating the fast formation of (Zn,Cu) HDS from the ZnO thin film. Following the exposure of the ZnO surface to Cu(NO 3 ) 2 solution, ethanol-water solvent mixture was used to rinse the cell for 1 min.…”

“…Sets of spectra were analyzed by integrating the peaks for $vfalse({\text{NO}}_3^{-}false)$ at ≈ 1420 cm −1 , v (C=C) at ≈ 1588 cm −1 and v as (OCO − ) at ≈ 1647 cm −1 . 33 We used peak areas to follow the extent of reaction during HDS formation from ALD ZnO as well as HDS conversion to HKUST-1.…”

“…The absorbance of the $vfalse({\text{NO}}_3^{-}false)$ peaks remains constant during the rinse step. When the H 3 BTC solution is dosed into the flow cell at t ≈ 3.5 min, four peaks appear (Figure 2a) which represent the symmetric and asymmetric stretching modes (1378 cm −1 and 1647 cm −1 , respectively) of the carboxylate groups in HKUST-1, 33 and the C=C vibration modes (1450 cm −1 and 1588 cm −1 ) associated with the aromatic ring in the BTC 3− . The decreased peak area of $vfalse({\text{NO}}_3^{-}false)$ and the increased peak area of v as (OCO − ) and v (C=C) were observed simultaneously (Figures 2b–d), consistent with the anion exchange process reported for HDS conversion to MOFs.…”

Ultra‐Fast Degradation of Chemical Warfare Agents Using MOF–Nanofiber Kebabs

“…[16] Conformal, high-quality MOF thin-films grown on nanofibers are yet to be explored for catalytic destruction of CWAs.H erein, we show that the half-lives of the nerve agent soman (O-pinacolyl methylphosphonofluoridate,a lso known as GD) are as short as 2.3 min using our MOF-nanofiber composite catalysts.This is also the first demonstration of effective destruction of areal CWAc ompound using MOF-fabric composites,a sprevious work has only investigated simulants. [21,22] Although our previous work has shown that Al 2 O 3 and ZnO ALD can also promote MOF growth on fibers, [17,23,24] these ALD films were not used as nucleation layers in this case due to substrate incompatibility with the Al 2 O 3 ALD process and instability of ZnO in the highly acidic solvothermal solution we used. This TiO 2 ALD layer is expected to promote MOF heterogeneous nucleation on fibers, [17] and provides some contribution to catalytic CWA detoxification.…”