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    Synthesis and characterization of PVDF supported silica immobilized phosphotungstic acid (Si-PWA/PVDF) ion-exchange membrane, Materials Letters,
    (Elsevier, 2013-06) Pandey, Jay
    An ion exchange membrane was synthesized by impregnating sub-micron sized silica-immobilized phosphotungstic acid (Si-PWA) particles on a porous (poly vinylidene fluoride) (PVDF) film. Surface morphology, crystalline nature and thermal stability of the membrane were studied. The membrane was found to have a defect free surface, which contained both crystalline and amorphous phases and was stable up to 350 °C. Electrochemical properties (transport number) of membranes of two different PWA/TEOS (tetraethoxyorthosilicate) ratios were compared and the one with a higher ratio gave better properties. Ion exchange capacity (IEC) of 0.82 meq/g and counter-ion transport number of 0.91 indicated good electrochemical properties of the membrane synthesized with sol of PWA/TEOS ratio of 1.5.
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    Zirconium phosphate based proton conducting membrane for DMFC application
    (Elsevier, 2015-08) Pandey, Jay
    A proton conducting poly(vinylidene fluoride) (PVDF) supported zirconium phosphate (ZrP) ion-exchange membrane (ZrP/PVDF) was synthesized for potential application in DMFC by filling the pores of a PVDF film with in-situ grown ZrP particles. Presence of labile protons attached to Pdouble bondO group was confirmed from 1H NMR and FT-IR characterizations. SEM micrographs showed defect-free top surface. The thermal stability and mechanical strength of the ZrP/PVDF membrane was better than Nafion-117. Water to methanol uptake ratio was higher while methanol cross-over for ZRP/PVDF membrane was lower than Nafion-117. Membrane possessed fair electrochemical properties; 0.85 static counter-ion transport number, 0.76 meqg−1 ion exchange capacity and 1.25 mScm−1 proton conductivity at 30 °C. DMFC performance of the synthesized membrane at 35 °C was compared with the Nafion-117. DMFC studies were also done at different operating conditions and the maximum peak power density was 32.3 mWcm−2 at 60 °C, 1 M methanol concentration and 60% relative humidity.
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    Design and synthesis of highly stable poly(tetrafluoroethylene)-zirconium phosphate (PTFE-ZrP) ion-exchange membrane for vanadium redox flow battery (VRFB)
    (Springer, 2017-01) Pandey, Jay
    Vanadium redox flow battery (VRFB) is a promising technology for large-scale renewable energy storage. Design of ion-exchange membrane (IEM) with desired properties like low-cost, mechanically chemically stable, low vanadium ion permeability and high proton conductivity is one of the major challenges. Here, we report the design and synthesis of novel poly(tetrafluoroethylene)-zirconium phosphate (PTFE-ZrP) asymmetric IEM using a simple brush coating method. XRD results confirmed the presence of α-ZrP crystalline phase onto the top layer of the membrane. Excellent mechanical strength was observed with burst pressure of 3.22 × 105 N m−2. Oxidative stability of membrane in Fenton’s reagent was much better than Nafion-115. Vanadium ion (V4+) permeability of the membrane was more than three times lower than that of Nafion-115. Single-cell VRFB with PTFE-ZrP membrane showed ∼80% energy efficiency below 30 mA cm−2. Very high columbic efficiency ∼100% of VRFB with PTFE-ZrP membrane confirmed little contamination of electrolyte due to cross-mixing.