Anhydrous proton-conducting organic–inorganic hybrid membranes synthesized from tetramethoxysilane/methyltrimethoxysilane/diisopropyl phosphite and ionic liquid

Abstract

Inorganic-organic hybrid membranes were prepared by sol-gel process with tetramethoxysilane/ methyltrimethoxysilane/diisopropyl phosphite and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF 4 ) ionic liquid as precursors. The Fourier transform infrared spectroscopy (FT-IR) and 31 P, 29 Si, 1 H, 13 C, and 19 F nuclear magnetic resonance measurements have shown good chemical stability and complexation of (POH [(CH 3 ) 2 CHO] 2 ) with [BMIMBF 4 ] ionic liquid in the fabricated hybrid membranes. The influence of the textural properties of all the prepared composite membranes could be interpreted from nitrogen adsorption-desorption measurements. The average pore size was increased proportionally with the ionic liquid weight percent ratio in the host phosphosilicate matrix from 2.59 to 11.71 nm, respectively. Thermogravimetric analysis and differential thermal analysis measurements confirmed that the hybrid membranes were thermally stable up to 260°C. Thermal stability of the hybrid membranes was significantly enhanced by the presence of inorganic SiO 2 framework and high stability of [BF 4 ] anion. For all the composite membranes, the conductivities were measured within the temperature range (−30°C) to 150°C, and a maximum conductivity of 7×10 −3 S/cm at 150°C was achieved for 40 wt.% ionic liquid-based composite membrane under nonhumidified conditions.

Anhydrous Proton Conducting Hybrid Membrane Electrolytes for High Temperature (>100°C) Proton Exchange Membrane Fuel Cells

“…For all the prepared hybrid membranes, the interaction between the doped "hydrophilic" [BMIMBF 4 ] ionic liquid and the inorganic phosphosilicate network was investigated by Fourier transform infrared spectroscopy and 31 P, 1 H, and 13 C MAS NMR measurements. Several spectral bands shifting in FTIR spectra, and chemical shifts shifting in 31 P, 1 H, and 13 C NMR spectra of these hybrid membranes compared with pure ionic liquid confirmed the interaction of doped ionic liquid and inorganic phosphosilicate network at molecular scale. The textural properties were investigated from nitrogen adsorption-desorption analysis.…”

“…Spectral band centered at 795 cm À1 is due to the symmetric stretching of the P-O-P and Si-O-Si (bridging oxygen atoms between the tetrahedral) bonds. Within the wavenumber range 400-4000 cm À1 several spectral bands are identified for 31,32 It should be emphasized that all the phosphosilicate matrices related spectral bands within the wavenumber range 400-1200 cm À1 are overlapped well with ionic liquid related spectral bands. According to previous study, multiple hydrogen bonds should be formed between the alkyl C-H and ring C-H of BMIM þ and BF 4…”

“…The spectral bands within the wavenumber range 400-880 cm À1 are attributed to the Si-O-Si bond bending vibrations and symmetric stretching vibrations of Si-O-Si bonds, respectively. 12,31,32 In the selected phosphosilicate matrix, the IR absorption band appeared at 873 cm À1 is assigned to P-O-P asymmetric stretching mode. Spectral band centered at 795 cm À1 is due to the symmetric stretching of the P-O-P and Si-O-Si (bridging oxygen atoms between the tetrahedral) bonds.…”

“…NMR spectroscopic techniques can be used to study ionic interactions and ionic states. Figure 5 shows (a) 31 P, (b) 1 H, and (c) 13 C MAS NMR spectra of all the prepared hybrid membranes, respectively. From the 31 P MAS NMR spectra (Fig.…”

Electroactive Conjugated Polymer / Magnetic Functional Reduced Graphene Oxide for Highly Capacitive Pseudocapacitors: Electrosynthesis, Physioelectrochemical and DFT Investigation

“…In addition, ionic liquids have also low viscosities with high conductivities advantages made them to employ in electrochemical devices for fast charge-discharge conditions. Pyrrolidinium and imidazolium are two main applied ionic liquids in electrochemical investigations [26][27][28][29]. Pyrrolidinium compared to imidazolium indicated larger electrochemical stability window (ESW) favorable for SCs operating at higher voltage or contributing mainly to the energy density.…”