Layer-by-layer decoration of MOFs on electrospun nanofibers

Abstract

The design and fabrication of novel organic-inorganic nanocomposite membranes using metal-organic frameworks as building blocks have attracted numerous scientists. Here, HKUST-1 particles were decorated on crosslinked polymer nanofibers through a layer-by-layer method. The immersion sequence, the crosslinking and the number of the deposition cycles have a significant impact on the formation of the HKUST-1 decorated nanofibrous membranes. Moreover, it has been shown that such a membrane could be applied as a catalyst for visual detection of hydrogen peroxide.

Fig. 1. SEM images of the pristine PAA/PVA nanofibers (a), the crosslinked PAA/PVA nanofibers (b), MOF-decorated nanofibers after 1 cycle of growth (c), MOF-decorated nanofibers after 2 cycle of growth (d), MOF-decorated nanofibers after 4 cycle of growth (e) and MOF-decorated nanofibers after 8 cycle of growth (f). The insets are the corresponding photos of the membranes.

Fig. 2. XRD patterns (a), FTIR spectra (b) and TG curves (c) of the PAA/PVA nanofibers, the HKUST-1 powder and the HKUST-1 decorated nanofibers after different cycles of growth.

Fig. 3. SEM images of various nanofiber membranes. (a) The nanofibers were immersed only into the metal ion solution for 2 h; (b) the nanofibers were immersed into the ligand solution first and then into the metal ion solution; the decoration of HKUST-1 on the nanofibers after crosslinking for 30 min (c) and 1 h (d), and the growth process was identical with the sample in Fig. 1c (after crosslinking for 15 min).

Fig. 4. UV-vis spectra of the solutions consisted of (a) OPD and H₂O₂, (b) HKUST-1 decorated nanofiber membrane and H₂O₂, (c) OPD, (d) OPD and HKUST-1 decorated nanofiber membrane, (e) OPD, H₂O₂ and HKUST-1 decorated nanofiber membrane. The inset is the corresponding photo of the solutions.

Fig. 5. (a) UV-vis spectrum of the mixed solution of OPD and H₂O₂ after the addition of 100 μL of 1 mM Cu(OAc)₂ solution; (b) the peak intensity at 418 nm was recorded to test the recyclability of the HKUST-1 decorated nanofiber membrane for the detection of H₂O₂.