Poly(vinylidene fluoride-co-hexafluoro propylene) is a prospective material for the fabrication of polymer electrolyte membranes (PEMs) for direct methanol fuel cells, primarily due to its low methanol permeability, high mechanical integrity and significantly low cost compared to conventionally used Nafion. However, low proton conductivity has hindered its independent use; therefore, most studies on this prospective copolymer have been done by using it in conjunction with Nafion. Nevertheless, partial sulfonation of this copolymer has resulted in increased proton conductivity while maintaining its low methanol permeability. Therefore, it seems appropriate that blending this sulfonated copolymer with a second low-cost component, which can complement its low conductive nature, can result in PEMs with high selectivity. Use of partially sulfonated polyaniline, as the second component, produced selectivity ratio of 5.85×105Sscm-3, ion-exchange capacity of 0.71meqg-1, and current density of 90.5mAcm-2 at +0.2V and 60°C and corresponding maximum power density of 18.5mWcm-2. © 2013 Elsevier Ltd.

K DUTTA

S DAS

P KUMAR

P P KUNDU

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Applied Energy

To develop a cost-effective efficient non-noble cathode electrocatalyst with enhanced oxygen reduction is one of the major concerns in optimizing electrical efficiency in microbial fuel cells (MFCs). The study here demonstrates the evaluation of synthesized non-noble bi-metallic [1:1 Nickel (Ni): Cobalt (Co)] nanocatalyst supported on sulfonated polyaniline (SPAni) in MFC. The homogeneous dispersion of nanoparticles on supporting matrix was confirmed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Inductive coupled plasma - optical emission spectroscopy (ICP-OES) also shows the uniform distribution of (1:1) Co and Ni nanoparticles over the polyaniline hetero-structure for Ni-Co/SPAni and Ni-Co/PAni nanocatalyst system. Furthermore, the high specific surface area [Multipoint Brunauer-Emmett-Teller (MBET)] of Ni-Co/SPAni catalyst associated with the uniform dispersion and high porosity makes it promising catalyst material for fuel cell applications. Among all the synthesized electrocatalysts, 1:1 Ni-Co/SPAni catalyst revealed the highest catalytic activity with the enhanced stability towards oxygen reduction reactions (ORR). Moreover, in MFC, a maximum power density of ∼659.79 mWm−2 was observed with prospective Ni-Co/SPAni catalyst compared to the corresponding Pt/C catalyst (∼483.48 mWm−2). The results indicate the potential application of a conducting polymer such as SPAni as supporting matrix in bimetallic Ni-Co catalyst system that could alternatively serve as an efficient cathode catalyst over the traditionally used costly Pt/C catalyst in MFCs operation. © 2018

Electrochimica Acta

Development of highly efficient bimetallic nanocomposite cathode catalyst, composed of Ni:Co supported sulfonated polyaniline for application in microbial fuel cells

Presently, rechargeable Li-ion batteries, possessing highest energy densities among all batte-ries, are used in a major fraction of all portable electronic devices. However, for bestowing the Li-ion batteries suitable for such advanced applications, further improvements in the energy densities (Li-capacities) and in the cycle life are essential. In a broader sense, this can be achieved by replacing the presently used electrode materials by materials possessing higher Li-capacities and minimization of the degradation of such materials with electrochemical cycling. It has been realized that the major reason for degradation in battery performance in terms of capacity with cycling is the disintegration/fragmentation of the active electrode materials due to stresses generated during Li-intercalation/de-intercalation in every cycle. Such stresses arise from the reversible volume changes of the active electrode materials during Li-insertion and removal. In quest of higher energy densities, replacement of the presently used graphitic carbon by potentially higher capacity metallic anode materials (like Si, Sn, and Al) is likely to further accrue this stress related disintegration due to ∼30 times higher volume changes experienced by such materials. It has also been recently realized that passivating layer formed on the surface of the electrodes also contributes toward the stress development. After briefly introducing the mechanistic aspects of Li-ion batteries, this article focuses on the reasons and consequences associated with stress developments in different electrode materials, highlighting the various strategies, in terms of designing new electrode com-positions or reducing the microstructural scale, that are being presently adopted to address the stress-related issues. Considering that experimental determination of such stresses is essential toward further progress in Li-ion battery research, this article introduces a recently reported technique developed for real-time measurement of such stresses. It finally concludes by raising some critical issues that need to be resolved through further research in this area. © 2016 Taylor & Francis Group, LLC.

Critical Reviews in Solid State and Materials Sciences

Materials for Electrodes of Li-Ion Batteries: Issues Related to Stress Development

Bimetallic Ni-Ag alloy nanostructures with different ratios of Ni and Ag, prepared through a simple co-reduction process from the respective precursor metal salts, were employed as the electrocatalysts toward methanol oxidation reaction in acidic electrolyte. The previously reported superior catalytic performance exhibited by deposited Ni catalyst on sulfonated polypyrrole (SPPy) matrix is encouraging enough to further utilize SPPy as a support matrix and Ni as a primary metal catalyst. In this work, the activity of the synthesized Ni based catalyst was strongly dependent on the composition of the Ni-Ag/SPPy catalyst systems. The best performance was obtained upon utilizing a Ni:Ag ratio of 80:20. For example, this Ni-Ag (80:20)/SPPy catalyst system exhibited a higher area specific current density, a stable current density, a higher IF/IB ratio and a better single cell DMFC performance in acidic electrolyte, than that of the other prepared catalyst systems, and also, the state-of-the-art Pt-Ru on C. © 2016 IEEE.

International Conference on 21st Century Energy Needs - Materials, Systems and Applications, ICTFCEN 2016

Electrocatalytic potential of sulfonated polypyrrole-supported Ni-Ag towards methanol oxidation in acidic medium

Sulfonation of polyvinylidinefluoride (PVdF) with chlorosulfonic acid for 2 hours revealed a respective 33% degree of sulfonation (DS) in a SPVdF membrane. The resulting sulfonated PVdF resins were used for Nafion 117 modification as coat and laminating materials, where the modified Nafion 117 membranes (laminated and coated with SPVdF) were used as polymer electrolyte membranes in microbial fuel cells (MFCs). Coating/lamination exhibited reduced oxygen diffusion across membranes by a magnitude of less than two orders over a pristine Nafion 117 membrane. This resulted in higher open circuit voltages (OCVs) with increased coulombic efficiency (CE) in MFCs. With SPVdF coated and laminated Nafion 117 membranes, respective IEC values of 0.57 and 0.46 meq g-1 and proton conductivities of 5.91 × 10-3 and 5.11 × 10-3 S cm-1 were observed, indicating maximum power and current densities of 446.45 ± 21 mW m-2 &amp; 1721.78 ± 86 mA m-2 and 413.79 ± 20 mW m-2 &amp; 1657.57 ± 82 mA m-2 in MFCs using mixed Firmicutes as biocatalysts. The obtained coulombic efficiencies were higher (approx. 1-2%) than those of pristine Nafion 117, indicative of its reduced oxygen diffusion at the anode. In effect, the study enumerates the efficiency of modified Nafion 117 with sulfonated PVdF coated and laminated membranes as a separating barrier in single-chambered MFCs for microbial bio-energy conversion. © The Royal Society of Chemistry 2016.

RSC Advances

Fabrication of laminated and coated Nafion 117 membranes for reduced mass transfer in microbial fuel cells

Poly(vinylidene fluoride) (PVdF) and polyaniline (PAni) were partially sulfonated, using chlorosulfonic acid (CSA) as the sulfonating agent. The prepared partially sulfonated PVdF (SPVdF), having a degree of sulfonation ~22%, and the partially sulfonated PAni (SPAni), having a degree of sulfonation ~29%, were blended at constituent wt% ratios of SPVdF:SPAni = 95:5, 90:10, 85:15 and 80:20 in order to fabricate different blend membranes. These blend membranes exhibited extremely low methanol uptake and methanol permeability, as well as, high membrane selectivity ratios (especially at high methanol concentrations) The blend membranes also exhibited superior water uptake capacity, water swellability, ion-exchange capacity and proton conductivity, compared to the pristine PVdF and SPVdF membranes. The SPVdF:SPAni (80:20) blend membrane was found to produce the best results in terms of exhibiting the lowest methanol permeability values of 1.50×10-9 cm2s-1 (at 2 M methanol) and 6.30×10-9 cm2s-1 (at 8 M methanol), and the highest membrane selectivity values of 3.27×106 Sscm-3 (at 2 M methanol) and 7.78×105 Sscm-3 (at 8 M methanol). On the other hand, introduction of Nafion within the SPVdF/SPAni blend membrane, to form a ternary blend membrane (i.e. SPVdF:Nafion:SPAni = 50:30:20), resulted in much improved ion-exchange capacity and proton conductivity.

Fulltext

Polymer Journal

Effect of the presence of partially sulfonated polyaniline on the proton and methanol transport behavior of partially sulfonated PVdF membrane

Search for suitable materials for fabricating polymer electrolyte membranes (PEMs) for application in polymer electrolyte membrane fuel cells, and particularly in direct methanol fuel cells (DMFCs), has been an important field of research for the last several decades. Notable candidates that have emerged from this extensive and seemingly exhaustive research are Nafion®, poly(vinylidenefluoride), sulfonated poly(etheretherketone), poly(benzimidazole), Dow XUS®, Flemion® R, 3P-energy, Aciplex-S®, Gore-Tex®, Gore-Select®, and their different blends, copolymers and interpenetrating networks with compounds, such as poly(hexafluoropropylene), poly(acrylonitrile), poly(styrenesulfonate), and poly(methylmethacrylate). Nevertheless, the objective of achieving a much reduced methanol crossover, while maintaining a substantial level of proton conductivity, has remained by and large elusive. However, a ray of hope has been provided by conducting polymers (CPs), and this has led to a considerable number of researchers to plunge into the exploitation of this possibility. This review focuses on the application of CPs, mainly polyaniline and polypyrrole, as PEM constituents. Detailed comparisons between their functioning, and their respective utility in terms of achieving this objective have been provided. We have also discussed the following critical points: first, the effect of CPs on methanol crossover, proton conductivity, and gas diffusion, and second, thermal stability of CPs in the temperature range within which DMFC operates. © 2014 Taylor and Francis Group, LLC.

Polymer Reviews

Utilization of conducting polymers in fabricating polymer electrolyte membranes for application in direct methanol fuel cells

Establishing a better coordination between operating parameters and flow channel design is one of the most critical factors in achieving an optimum final performance of a fuel cell, since even a marginal change in any of the parameters can sharply affect the cell's performance. In this study, we report the use of three different acids, viz. sulphuric acid (H2SO4), formic acid (HCOOH) and phosphoric acid (H3PO4) as supporting electrolytes in combination with 2 M methanol fuel, wherein we demonstrated the effects of different combinations of acidic fuels and channel designs on the final cell performance. For this purpose, we made use of four different types of serpentine flow design. In the process, it was observed that an addition of 2 M concentrations of H2SO4 and H3PO4 enhanced the cell performance sharply in terms of current density, reaching values of 210 mAcm-2 and 180 mAcm-2, respectively, when analyzed at 0.2 V potential. This result was a considerable improvement over the current density value of 90 mAcm-2 achieved while using only 2 M methanol analyzed at the same potential. Moreover, the open-circuit voltage showed a value of greater than 0.6 V for both fuel samples. With a flow channel length of 650 mm (A5SF2) and at an open ratio of 52%, we obtained maximum power values of 42 mWcm-2 and 36 mWcm-2 for fuels containing 2 M H2SO4 (M2S2) and 2 M H3PO4 (M2P2), respectively, when analyzed at 70°C. © 2013 John Wiley &amp; Sons, Ltd.

International Journal of Energy Research

Enhanced performance of direct methanol fuel cells: A study on the combined effect of various supporting electrolytes, flow channel designs and operating temperatures

Amphiphilic assemblies (AAs) are known to interact with polyelectrolytes in such a manner that the dynamic AAs retain their structural features, but the polyelectrolytes undergo conformational changes. This article reports that a charge bearing, rigid, water insoluble and oxidized conjugated polymer, polyaniline, can withstand such conformational changes and at the same time force the AAs to disassemble. An interfacial setup, comprising of an aqueous/organic interface, was utilized to study the disassembly process and the subsequent phase transfer phenomenon of the in situ synthesized polymer. It has further been demonstrated that the phase transfer occurred only when the concentration of the amphiphile was at and above its critical aggregation concentration. Moreover, fine dispersions of polyaniline were obtained initially in the aqueous phase and later in the organic phase. These fine dispersions suggest possibilities for better processing of this otherwise "difficult to process" polymer. The disassembly phenomenon was followed by changes in fluorescence emission and UV-vis absorption spectra of an entrapped probe molecule, recorded before and after the interaction. Changes in particle size upon disassembly were studied by dynamic light scattering. Dispersions of the polymer in the two phases were realized from transmission electron micrographs and UV-vis absorption spectra of the dispersed polymer. © 2013 Elsevier Inc.

Journal of Colloid and Interface Science

Interaction between oxidized polyaniline and oppositely charged amphiphilic assemblies in an aqueous/organic biphasic system

Smart clean surfaces exhibiting reversible superhydrophilic to superhydrophobic transitions have been widely fabricated. A myriad of complex fabricating procedures have evolved over the years. Here, we demonstrate an apparently simple approach, wherein we utilized the attractive interaction between an unfabricated electropolymerized film and negative charge bearing amphiphilic molecules to precisely control the hydrophobicity of the surface of the film. We also demonstrate the use of different hydrophobic molecules to plug the voids created by the uneven distribution of the attached amphiphiles' long hydrocarbon tails on the film surface. Water drop contact angle revealed that by the used technique, surface hydrophobicity can be tuned to any desired value. Moreover, the film surface exhibited a high adhesive force toward the water droplets, thus preventing them from rolling or dropping down. In addition, the tuning process can be completely reversed and repeated by altering the applied potential. The interaction between the amphiphiles and the film surface was confirmed by ATR-IR. Scanning electron micrographs revealed that the film surface underwent no morphological modifications upon interaction with the amphiphiles. © 2013 Elsevier Inc.

Amphiphiles as hydrophobicity regulator: Fine tuning the surface hydrophobicity of an electropolymerized film

Polymer films that respond to a variety of stimuli are attractive candidates for location-specific guest molecule delivery. These systems release the guest molecules by polymer erosion; thus, these are mono-use systems. If a polymer film is used to disassemble amphiphilic assemblies containing sequestered guest molecules, the polymer erosion issue can be circumvented. However, charge-bearing vinyl polymers, upon interaction with amphiphilic assemblies, are known to adapt to a conformation that results in encapsulating guest molecules instead of releasing them. On the contrary, it has earlier been reported that a rigid, charge-bearing, and water-insoluble conjugated polyaniline film can effectively disassemble amphiphilic assemblies without causing much harm to the film. Herein, we demonstrate the effect rendered by varying the electropolymerization potential on the interaction efficiency between the positive charge-bearing polyaniline film and oppositely charged amphiphilic assemblies. In addition, it is also demonstrated that a film of oxidized polyaniline can be regenerated for repetitive disassembly of the amphiphilic assemblies, and concomitant guest molecule delivery. © 2013 American Chemical Society.

Journal of Physical Chemistry B

Reversible assembly and disassembly of amphiphilic assemblies by electropolymerized polyaniline films: Effects rendered by varying the electropolymerization potential

Polymer electrolyte membrane with high selectivity ratio for direct methanol fuel cells: A preliminary study based on blends of partially sulfonated polymers polyaniline and PVdF-co-HFP

Journal	Data powered by TypesetApplied Energy
Publisher	Data powered by TypesetElsevier Ltd
ISSN	0306-2619