Using a sol-gel technique, organic-inorganic hybrid membranes were prepared using chitosan and mixed silica precursors such as tetraethoxysilane and γ-glycidoxypropyltrimethoxysilane. The γ-glycidoxypropyltrimethoxysilane acted as a coupling agent to enhance the compatibility between the organic (chitosan) and the inorganic (tetraethoxysilane) phase. Different techniques such as Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were employed to study the physicochemical changes in the resulting membranes. These membranes were tested for their ability to separate water + isopropanol mixtures by pervaporation in the temperature range of (303 to 323) K. The experimental data demonstrated that both flux and selectivity were increased simultaneously with increasing the amount of γ-glycidoxypropyltrimethoxysilane. However, this trend no longer remained when the content of γ-glycidoxypropyltrimethoxysilane was increased beyond 0.25 mass fraction. The membrane containing 0.25 mass fraction of γ-glycidoxypropyltrimethoxysilane (M-2) exhibited the highest separation selectivity of 18 981 with a thickness-normalized flux of 7.45 · 10 -7 kg · m -1 · h -1 at 303 K. The total flux and flux of water were found to be overlapping with up to 0.25 mass fraction of γ-glycidoxypropyltrimethoxysilane, suggesting that these membranes could be used effectively to break the azeotropic point of water-isopropanol mixtures. From the temperature-dependent permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (E pw ) are significantly lower than those of isopropanol permeation (E pIPA ), suggesting that the developed membranes have demonstrated an excellent separation performance for water-isopropanol systems.

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Mixed transition-metal oxides are emerging electrode materials, because of their higher electrochemical performances. In the present work, single-metal oxides, binary-metal oxides, and ternary mixed-metal oxides (MMOs) of zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) are successfully prepared by simple gel-combustion process. The structure and properties of MMOs are of great interest, because of the opportunity to tune their properties for better multifunctional performance than single and binary metal oxides. The crystal structure, functional group, surface morphology, and binding energy of all of the single, binary, and ternary MMOs are studied through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron microscopy (XPS), respectively. The entire electrochemical studies are also performed using cyclic voltammetry (CV), galvanostatic charge−discharge (GCD), and electrochemical impedance spectroscopy (EIS). From the electrochemical study, the ZnO−NiO−CuO MMOs electrode was found to possess pseudocapacitor-type features and shows an outstanding specific capacitance of 1831 F g −1 at a current density of 1 A g −1 , which is higher than that of single and binary metal oxides. The fabricated asymmetric (ASC) device [ZnO−NiO−CuO MMOs || r-GO] exhibits maximum specific capacitance of 118 F g −1 at the current density of 1 A g −1 . Hence, it leads to the supercapacitance property of maximum storage response; the ASC device possessed the excellent retentivity of (89.97%) up to 10 000 repeated cycles. The ASC device reveals a maximum specific power of 5672 W h kg −1 with a specific energy of 15.7 W h kg −1 with a high current density of 10 A g −1 . This finding shows that the ZnO−NiO−CuO MMOs can be used as potential electrode material and might have promising applications in high-performance energy storage devices.

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