Highly Adsorptive, MOF‐Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition

Abstract

While metal‐organic frameworks (MOFs) show great potential for gas adsorption and storage, their powder form limits deployment opportunities. Integration of MOFs on polymeric fibrous scaffolds will enable new applications in gas adsorption, membrane separation, catalysis, and toxic gas sensing. Here, we demonstrate a new synthesis route for growing MOFs on fibrous materials that achieves high MOF loadings, large surface areas and high adsorptive capacities. We find that a nanoscale coating of Al2O3 formed by atomic layer deposition (ALD) on the surface of nonwoven fiber mats facilitates nucleation of MOFs on the fibers throughout the mat. Functionality of MOFs is fully maintained after integration, and MOF crystals are well attached to the fibers. Breakthrough tests for HKUST‐1 MOFs [Cu3(BTC)2] on ALD‐coated polypropylene fibers reveal NH3 dynamic loadings up to 5.93 ± 0.20 mol/kg(MOF+fiber). Most importantly, this synthetic approach is generally applicable to a wide range of polymer fibers (e.g., PP, PET, cotton) and MOFs (e.g., HKUST‐1, MOF‐74, and UiO‐66).

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

“…It is also important to minimize the volume and weight of the active materials to reduce the burden for end users while maintaining substantial long‐term protection. In contrast, MOF thin films immobilized on functional substrates can simplify the handling and deployment, and are likely to promote MOF applications in CWA detoxification.…”

“…Free‐standing polyamide‐6 (PA‐6) nanofiber mats obtained from electrospinning were coated with a conformal thin‐layer (≈5 nm thick) of TiO 2 using atomic layer deposition (ALD). This TiO 2 ALD layer is expected to promote MOF heterogeneous nucleation on fibers, and provides some contribution to catalytic CWA detoxification . Although our previous work has shown that Al 2 O 3 and ZnO ALD can also promote MOF growth on fibers, 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.…”

“…SEM images (Figures b–d) show that UiO‐66‐NH 2 crystals (average size=126±25 nm) were grown conformally on the PA‐6@TiO 2 nanofibers. While we and other groups have attempted various methods to deposit UiO‐66‐type MOFs onto polymeric fibers in the past, only the method reported here enables the formation of these unique MOF–nanofiber kebab structures. In contrast, the growth of UiO‐66‐NH 2 on PA‐6 nanofibers without TiO 2 nucleation layers is patchy and does not result in a conformal thin‐film on the nanofiber surface as that on TiO 2 ‐coated PA‐6 nanofibers using the same synthesis conditions (Figure S1).…”

Water‐Based Assembly of Polymer–Metal Organic Framework (MOF) Functional Coatings

“…Metal organic frameworks (MOFs) are a diverse class of materials with extremely high porosity and tunable functionality. They have been explored for applications such as catalysis, gas adsorption and storage, energy storage, sensors, and separations . However, there is an intense need to translate MOFs into thin films and coatings so as to impart MOF‐like functionality into an underlying object that might otherwise not bear those qualities.…”

An Efficient Synthesis Strategy for Metal-Organic Frameworks: Dry-Gel Synthesis of MOF-74 Framework with High Yield and Improved Performance

“…These properties have made them superior to other traditional porous materials, and interest in their use for applications in gas/vapor sorption, molecular separation, and heterogeneous catalysis has increased significantly1678910111213. In spite of their tremendous potential, near-term prospects for commercial applications remain quite limited because of the lack of technologies and processes for synthesizing these materials in quantities required for industrial applications and at a low cost.…”