Sulfonated poly(vinylidene fluoride-co-hexafluoro propylene) (SPVdF-co-HFP) and polyaniline (PAni) have shown promise as polymer electrolyte membrane (PEM) materials, especially in direct methanol fuel cells, by virtue of their significantly high ion-exchange capacity (IEC) and membrane selectivity ratio. It was intuited that utilization of PAni nanostructures, with high surface areas, in PEMs can result in further improvement of these attributes. With this objective, positively-charged PAni nanofibers (NFs) were synthesized. Interestingly, when these NFs were exposed to a negatively-charged amphiphile solution for different time extents and followed by washing with an organic solvent, PAni nanowhiskers (NWs) having lengths between 40-120 nm and diameters between 10-40 nm were formed. BET surface area exhibited an increase upon decrease in the aspect ratio of the NFs. Membranes were fabricated using SPVdF-co-HFP as the continuous phase and PAni granules, NFs or NWs as the dispersed phase. SPVdF-co-HFP/PAni NWs and SPVdF-co-HFP/PAni NFs membranes exhibited enhanced IECs, proton conductivities and selectivities compared to SPVdF-co-HFP/PAni granules membrane. However, comparisons between SPVdF-co-HFP/PAni NFs and SPVdF-co-HFP/PAni NWs membranes revealed that the extended conjugation available for the former versus the higher surface area of the latter played a crucial role in determining the uptake and transport properties of the membranes. © The Royal Society of Chemistry.

K DUTTA

S DAS

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.

&nbsp;

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.

&nbsp;

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

RSC Advances

The quest for an efficient catalyst support material for improved deposition of electrocatalyst nanaoparticles towards application in methanol oxidation reaction has been an active field of research for last few decades. The use of highly expensive, although efficient, platinum-ruthenium (Pt-Ru) catalyst demands its minimum loading requirement and maximum utilization. We, herein, propose the potentiality of polyaniline (PAni) nanostructures-based catalyst support materials towards this utilization aspect. It was realized that the PAni nanowhiskers (NWs) support exhibited better dispersion and higher utilization of the deposited Pt-Ru nanoparticles, as compared to the PAni nanofibers (NFs) and the commercial Vulcan carbon (C) supports. This led to the exhibition of higher electrocatalytic activity, suppressed catalyst poisoning and better stability by the Pt-Ru/PAni NWs catalyst system. The charge transfer rates of the catalyst systems were found to be in the order Pt-Ru/PAni NWs > Pt-Ru/PAni NFs > Pt-Ru/C. Moreover, the Pt-Ru/PAni NWs catalyst system demonstrated the lowest solution resistance and the best performance in a direct methanol fuel cell (DMFC). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Fuel Cells

Nanostructured Polyaniline: An Efficient Support Matrix for Platinum-Ruthenium Anode Catalyst in Direct Methanol Fuel Cell

Nano-Al2O3 is incorporated within the blend of sulfonated PVDF-co-HFP/Nafion in varying molar ratios for the preparation of nanocomposite membranes. A series of tests namely, water uptake, swelling ratios, ion-exchange capacity (IEC), proton conductivity, oxygen diffusivity, etc. were conducted to analyze its capability in a microbial fuel cell (MFC). The enhanced water uptake, proton conductivity, and oxygen diffusivity results were observed with increasing nano-Al2O3 in the membrane. The sample A5, containing 5 wt% nano-Al2O3, exhibited superior proton conductivity over a naive SPVdF-co-HFP (∼88%) and Nafion 115 membrane (∼3.5%). In addition, this prospective membrane revealed comparable ion exchange capacity and reduced oxygen diffusivity than the corresponding Nafion 115. Furthermore, the electrical efficiency of this particular membrane was determined in single chambered MFCs as a constituent of a membrane electrode assembly. Employing mixed Firmicutes as biocatalysts, a maximum power and current density of 541.52 ± 27 mW m-2 and 1900 ± 95 mA m-2 were observed from MFC, which revealed an overall ∼48 and 11% increase over the naive SPVdF-co-HFP and Nafion 115 membrane. With a marked lowering in impedance, the results indicate the relevance of the Al2O3 filled nanocomposite as a separating barrier in single chambered MFCs for microbial bio-energy conversion. © The Royal Society of Chemistry 2016.

A nanocomposite membrane composed of incorporated nano-alumina within sulfonated PVDF-co-HFP/Nafion blend as separating barrier in a single chambered microbial fuel cell

Partially sulfonated poly(vinylidene fluoride-co-hexafluoro propylene)/partially sulfonated polyaniline (SPVdF-co-HFP/SPAni) binary blend membranes have shown promising results in terms of low methanol permeability and high membrane selectivity compared to Nafion-117 membrane. However, the proton conductivity and IEC of this binary blend membrane was much lower than Nafion-117. It was found that incorporation of minimal quantity of Nafion within SPVdF-co-HFP/SPAni blend membrane at a constituent weight % ratio of SPVdF-co-HFP:SPAni:Nafion = 50:40:10 induced significant improvements in ion-exchange capacity (IEC), proton conductivity and tensile strength over that of the binary blend membrane. In addition, the SPVdF-co-HFP/SPAni/Nafion ternary blend membrane exhibited much lower methanol permeability, higher membrane and relative selectivities and comparable IEC to Nafion-117. In effect, presence of minimal quantity of Nafion induced significant positive attributes to the ternary blend membrane; and assisted in reaching a balance between material cost and properties. © 2015 Wiley Periodicals, Inc.

Journal of Applied Polymer Science

Highly methanol resistant and selective ternary blend membrane composed of sulfonated PVdF-co-HFP, sulfonated polyaniline and nafion

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

Partially sulfonated poly(vinylidene fluoride) (SPVdF) has been prepared by incorporation of sulfonic acid groups within poly(vinylidene fluoride), using chlorosulfonic acid as the sulfonating agent. The degree of sulfonation (DS) has been varied by modulating the duration of the sulfonation reaction. Blending of SPVdF (having DS = 36.78%) with Nafion at a constituent wt.% ratio of SPVdF:Nafion = 70:30 has resulted in the fabrication of polymer electrolyte membrane with superior properties compared to pristine Nafion-117 membrane. This particular blend composition exhibited a proton conductivity value of 3.6 × 10-2 S cm-1 (i.e. ∼12.5% increase over Nafion-117), a methanol permeability value of 6.81 × 10-7 cm2 s-1 at 6M methanol concentration (i.e. ∼99.31% decrease from Nafion-117) and a corresponding membrane selectivity value of 5.29 × 104 Ss cm-3 (i.e. an increase of approximately two-orders of magnitude over Nafion-117) at 20 °C. In addition, this blend composition has also exhibited (a) better heat stability at temperatures as high as 160 °C by virtue of it possessing higher glass transition temperature, (b) higher storage modulus, (c) higher stress relaxation at high angular frequency and (d) superior DMFC performance at high methanol feed concentration in presence of humidified, as well as, non-humidified air as the catholyte, compared to Nafion-117 membrane. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Partially Sulfonated Poly(vinylidene fluoride) Induced Enhancements of Properties and DMFC Performance of Nafion Electrolyte Membrane

Nano-Al2O3 was incorporated into the blend of sulfonated-PVdF-co-HFP/Nafion using NMP (1-methyl-2-pyrrolidone) as a common solvent with the aim to develop an alternate membrane to be used in a single cell direct methanol fuel cell (DMFC). Furthermore, the synthesized nano-composite membranes were subjected to different tests such as FTIR, XRD, water uptake, swelling, IEC (ion exchange capacity), proton conductivity and methanol crossover. The water uptake results indicated that with an increase in the nano-Al2O3 content (up to 5% w/w) in the blend, the water uptake of the nanocomposite matrix rapidly increased up to 34.8%. Sample S-5 composed of 5% (w/w) Al2O3 exhibited comparable proton conductivity/IEC, low methanol permeability and high membrane selectivity over the corresponding Nafion-117 membrane. In addition, the prospective nanocomposite membrane also exhibited comparable mechanical stability. Moreover, the maximum current density at 0.2 V in a single cell DMFC, which was operated with atmospheric air (without preheating/humidification) at the cathode, was recorded as 285 mA cm-2 and 270 mA cm-2 at 90 °C and 110 °C, respectively. Comparing the power densities of the single cell fitted with the membrane of Nafion-1 17 (28 mW cm-2) and blend of sulfonated-PVdF-co-HFP and Nafion (32 mW cm-2), the single cell with the composite membrane S-5 showed an optimum power density (57 mW cm-2) at +0.2 V at a high temperature of 90-110 °C. These results indicate that the composite membrane could effectively reduce the anhydrous conditions at high operating temperatures. © 2015 The Royal Society of Chemistry.

Journal	Data powered by TypesetRSC Advances
Publisher	Data powered by TypesetRoyal Society of Chemistry
ISSN	2046-2069