Direct Surface Growth Of UIO-66-NH₂ on Polyacrylonitrile Nanofibers for Efficient Toxic Chemical Removal

Direct solvothermal growth of the metal–organic framework (MOF) UiO-66-NH₂ on polymer surface was successfully demonstrated. By using acetone as the solvent for synthesis instead of <i>N</i>,<i>N</i>-dimethylformamide, polymers like polyacrylonitrile (PAN) can be used directly in the solvothermal synthesis step to grow MOF on the polymer surface. We use X-ray diffraction and FT-IR to confirm our method produces crystalline UiO-66-NH2 on the surface of electrospun PAN nanofibers. Characterization of this type of composite revealed up to 50 wt % MOF loading according to nitrogen isotherms. Since the MOFs are located on the surface of the polymer fibers, the composites are capable of high loadings of chlorine gas. Compared to electrospun composites made with preformed UiO-66-NH₂, the in situ method is a simple alternative that produces composites with higher MOF loading

Diffusion of CO₂ in Large Crystals of Cu-BTC MOF

Carbon dioxide adsorption in metal–organic frameworks has been widely studied for applications in carbon capture and sequestration. A critical component that has been largely overlooked is the measurement of diffusion rates. This paper describes a new reproducible procedure to synthesize millimeter-scale Cu-BTC single crystals using concentrated reactants and an acetic acid modulator. Microscopic images, X-ray diffraction patterns, Brunauer–Emmett–Teller surface areas, and thermogravimetric analysis results all confirm the high quality of these Cu-BTC single crystals. The large crystal size aids in the accurate measurement of micropore diffusion coefficients. Concentration-swing frequency response performed at varying gas-phase concentrations gives diffusion coefficients that show very little dependence on the loading up to pressures of 0.1 bar. The measured micropore diffusion coefficient for CO₂ in Cu-BTC is 1.7 × 10^–9 m²/s