Journal Article 1-Int National J of Hydrogen Energy (original) (raw)
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International Journal of Hydrogen Energy, 2016
In this study, sulfated zirconia (SZ) nanoparticles were used as inorganic additives in order to improve physicochemical properties of sulfonated poly (ether ether ketone) (SPEEK) membranes especially for fuel cell application at intermediate temperature. Interactive effects of SPEEK sulfonation time and the content of incorporated additive (as the factors) were studied on the proton conductivity and the oxidative stability of the nanocomposite membranes (as the responses) through the response surface method (RSM) using the central composite design (CCD). The optimum parameters were 6.9 h sulfonation time and 5.94 wt. % of sulfated zirconia that represented proton conductivity of 3.88 mS cm À1 (at 100 C and 100% RH) and oxidative stability of 102 min. The sulfonation time had more effect on both responses. Furthermore, the addition of SZ nanoparticles improved both of oxidative stability and proton conductivity. The morphology, thermal and mechanical properties of optimized nanocomposite membrane were investigated by FESEM, TGA, DSC and tensile strength test, respectively. Also, the XRD, TGA, FTIR, EDX and TEM analysis were conducted to characterize the SZ nanoparticles.
Organic-Inorganic Composite Polymer Electrolyte Membranes, 2017
Proton-exchange membrane fuel cells (PEMFCs) are one of the most promising commercial technologies used to produce clean energy with high efficiency, energy density, and low emission of harmful gases. Proton-exchange membrane (PEM) is a major part of fuel cell that plays an important role. However, these membranes are very expensive, thermally degradable at high temperature, and conduct protons only in aqueous condition that limits the performance of PEMFC. However, at lower operating temperature, the performance of fuel cell is affected, due to slow electrode kinetics. Recently, great attention has been paid to develop high temperature-tolerant PEM with high proton conductivity. The organic-inorganic composite PEM that can work at high temperature with high proton conductivity is being developed. These organic-inorganic membranes are created by incorporation of metal oxide nanoparticles in the polymer host such as Nafion with strong acid site. These membranes provide high proton conductivity, and chemical and thermal stability to PEMs. Sulfated zirconia (S-ZrO 2), a strongest super acid possessing protogenic groups, is being used as an inorganic filler for composite membranes which showed improved operation at elevated temperature. This chapter presents an overview of the commonly used polymer hosts and inorganic additives. The available literature on S-ZrO 2 nanohybrid membrane technology has been discussed in view of catalyzing the future research to develop more suitable PEM for fuel cell.
Novel quaternized polysulfone/ZrO 2 composite membranes for solid alkaline fuel cell applications
Fuel and Energy Abstracts, 2011
Alkaline membrane fuel cell Zirconia Composite membrane Transmission electron microscopy a b s t r a c t A novel composite anion exchange membrane, zirconia incorporated quaternized polysulfone (designated as QPSU/ZrO 2 ), is prepared by solution casting method. The characteristic properties of the QPSU/ZrO 2 composite polymer membranes are investigated by thermogravimetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The morphology of the composite membrane is observed by SEM and TEM studies. A study of an alkaline membrane fuel cell (AMFC) operating with hydroxide ion conducting membrane is reported. Evaluation of the fuel cell is performed using membrane electrode assemblies made up of carbon supported platinum (Vulcan XC-72) anode and platinum cathode catalysts and QPSU/ZrO 2 composite membrane. Experimental results indicate that the AMFC employing a cheap non-perflourinated (QPSU/ZrO 2 ) composite polymer membrane shows better electrochemical performance. The maximum power density observed is 250 mW/cm 2 for QPSU/10% ZrO 2 at 60 C. The QPSU/ZrO 2 composite membrane constitutes a good candidate for alkaline membrane fuel cell applications. (D. Sangeetha).
Fuel and Energy Abstracts, 2011
Thermal stability Mechanical stability a b s t r a c t The paper describes the preparation of membranes based on sulfonated poly(ether ether ketone) [SPEEK] [degree of sulfonation w65%] in the presence of varying amounts of poly (ethylene glycol) (molecular weight 200) [PEG-200] and cyclohexane dimethanol [CDM] using water:ethanol (50:50) as solvent. After drying, the membranes were heat treated at 60 C (2 h), 80 C (2 h), 100 C (2 h), 120 C (2 h) and 135 C for 16 h. After the heat treatment, samples were insoluble in water:ethanol (50:50) mixture. The membranes thus obtained were characterized by FTIR spectroscopy (structural), water uptake (hydrolytic stability), thermal stability (TG), mechanical stability and proton conductivity. A significant increase in the hydrolytic stability was observed, SPEEK became elastic and fragile whereas the heat-treated SPEEK/PEG and SPEEK/CDM remained stable even after 135 days of water immersion at 35 C. (V. Choudhary).
International Journal of Hydrogen Energy, 2012
Copolymer Proton conductivity Proton exchange membrane Fuel cell a b s t r a c t A series of Sulfonated Poly (fluorenyl ether ketone) ionomers containing aliphatic functional segments were synthesized and characterized. The monomer 4,4 0 -Dihydroxy-a, u-diphenoxydecane with aliphatic group was conveniently prepared from hydroquinone and 1,10-dibromodecane. A series of sulfonated aliphatic functional groups containing poly-(fluorenyl ether ketone)s with different aliphatic group content were successfully synthesized and characterized in detail, in particular with respect to properties relevant for their application as membrane materials in proton exchange membrane (PEM) fuel cells. Tough and transparent membranes were formed by casting from their solutions. The effects of alkyl groups were investigated by comparison of the PEM properties of the copolymers with different content of aliphatic component on the copolymer chain. The introduction of aliphatic segments can provide an enhanced water uptake, increased proton conductivities, but worse oxidative stability. Transmission electron microscope (TEM) images of j and f revealed an improved phase separation structure under the effect of aliphatic groups. The
South African Journal of …, 2007
Polyacrylonitrile (PAN) was sulfonated and the membranes prepared were then characterized by the FTIR-ATR, Elemental Analyzer EA, TGA, DSC, SEM, Tensile, Water uptake and Impedance tests. FTIR-ATR spectra show the substitution of the sulfonic group (SO 3 ) to the main stem of the chain and also the hydrolysis of the cyanide group to amide group confirm the conversion of polyacrylonitrile to sulfonated polyacrylamide. Increase in water uptake property as compared to pure PAN also confirms the sulfonation process has occurred. Thermal properties also confirm the enhancement of the materials after sulfonation reaction.
Macromolecular Materials and Engineering, 2018
when operating at elevated temperatures, researchers have focused on heat-resistant materials as electrolytes for application at intermediate temperatures. [3-7] One of such materials is a type of hydrocarbon polymers known as poly(ether ether ketone) (PEEK) which is converted to sulfonated poly(ether ether ketone) (SPEEK) during an electrophilic sulfonation reaction. [8-15] Due to the fact that pristine SPEEK suffers from major drawbacks at higher temperatures, that is, above 100 °C, the fillers are introduced into polymeric matrix to overcome them. [16-18] For instance, numerous additives such as zeolite, [8] aluminum oxide, [19] single-walled carbon nanotubes, [20] and zirconium oxide [21,22] were embedded into SPEEK matrix and possessed great properties. Besides, Du et al. [23] studied the compatibility of silica sulfuric acid (SSA) particles with SPEEK by fabricating a series of SSA/ SPEEK membranes. The proton conductivity, distribution of ionic clusters, water retention, and thermal behavior of the prepared SSA/SPEEK membranes were promoted. [23] In addition, the composites of SPEEK and surface-functionalized TiO 2 (hydrophilic and hydrophobic TiO 2) additives were investigated by Di Vona et al. [24] It was proved that different types of functionalities on the surface of the filler make variation in physicochemical properties of prepared nanocomposite membranes. Likewise, titania nanosheet (TNS)/SPEEK membranes were another interesting candidates for electrolytes of fuel cells working at medium temperatures (T > 100 °C). [25] Sulfated zirconia (SZ) superacid with favorable properties including high proton conductivity, thermal stability, and simple synthesis procedure, is considered a primary interest filler within composites. [26] The SZ fillers by representing a high conductivity of 3 mS cm −1 in Nafion/SZ composite membranes under completely dry condition received much attention for application in high-temperature fuel cells. [27] Zhang et al. [28] employed sulfated zirconia supported platinum catalyst (Pt-SZ) as a self-humidifying agent in SPEEK matrix for PEMFC application under low relative humidity condition. The Pt-SZ additives by providing additional acidic sites within the SPEEK/ Pt-SZ membrane made a general enhancement in terms of proton conductivity, power density, and water uptake (WU) at Sulfated Zirconia Fillers This study expresses that the characteristics of sulfated zirconia (SZ) nanostructure in sulfonated poly(ether ether ketone) (SPEEK)-based membranes is the key to optimize their properties for fuel cell applications. Two types of SZ treating in different thermal conditions are produced by precipitation and analyzed by X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. Sulfate concentration on both types of SZ is changing from 0.54 to 1.45 wt% and thus the SZ samples differ in particle size and sulfate content. The nanocomposite membranes are prepared by incorporating 6 wt% of SZ samples into SPEEK matrix in casting procedure followed by performing electrochemical characterizations and impedance spectroscopy. Moreover, morphology, mechanical, and chemical stability of the membranes are investigated by field emission scanning electron microscopy, stress-strain, and ex situ Fenton's tests. The incorporation of SZ sample having more surface sulfate groups in the SPEEK matrix results in not only excessive oxidative stability and tensile strength but also more acidic sites for ion transport, promoting conductivity. Furthermore, both types of nanocomposite membranes show improved ionic conductivity and water affinity with a lower tendency to swell rather than the plain SPEEK membrane. It is proved that desired consequences of doping SZ into SPEEK matrix can be intensified by changing the physicochemical properties of sulfated zirconia nanoparticles.
International Journal of Hydrogen Energy, 2017
The present research focused on investigation of physicochemical and electrochemical properties of proton exchange membranes based on sulfonated poly (ether ether ketone) (SPEEK) by using zirconia nanoparticles. Plain and nanocomposite SPEEK membranes with different loadings of microwave-induced gel combustion synthesized ZrO 2 were fabricated. Sulfonation of polymer and nanoparticle production was confirmed by H NMR and XRD, respectively. Physical, chemical, and electrochemical properties of membranes were investigated by SEM, IEC, WU, EIS, tensile stressestrain, TGA, Fenton, and hydrolytic stability tests. H NMR spectra represented a DS of 65% for the sulfonated polymer. The prepared nanocomposite membranes possess improved thermal and mechanical stability with higher hydrolytic stability and enhanced oxidative stability. In addition, nanocomposite membranes exhibited higher water uptake with lower IEC. The hygroscopic zirconia nanoparticles resulted higher proton conductivity of nanocomposite membranes at temperatures upper than 80 C in comparison with pristine SPEEK membrane. All results showed the fabricated nanocomposite membranes have good physicochemical properties and promising future of the introduced approach for PEMFC applications.
Reactive and Functional Polymers, 2020
In order to simultaneously improve the durability and performance of sulfonated poly (ether ether ketone) (SPEEK), series of hybrid membranes were prepared by doping an optimized amount of sulfated titania and sulfated zirconia-titania into the SPEEK matrix. The nanoparticles were synthesized using the sol-gel method and specified using XRD and EDS analysis. The solution casting method was used to prepare the membranes. Membrane characterization was performed through structural, morphological, thermochemical, and mechanical tests. The physicochemical characterization revealed that nanocomposite membranes are significantly improved compared with plain SPEEK. The single-cell performance test of nanocomposite based MEA record the power density peaks of 500mW cm −2 at 120°C and RH = 80%. Accordingly, sulfated metal oxide nanocomposite SPEEK-based membranes are promising alternative polymer electrolyte membranes for fuel cell applications.
Energy & Fuels, 2008
Poly(ether ether ketone) (PEEK) was sulfonated at various degrees with sulfuric acid and dissolved in N,Ndimethylacetamide (DMAc). Montmorillonite (MMT) clay was mixed with this solution and solvent-casted on a glass plate. A Fourier transfer infrared (FTIR) experiment of sulfonated samples showed O-H vibration at 3490 cm-1 and SdO peaks at 1085 and 1100-1300 cm-1. Thermogravimetry analyzer (TGA) experiments revealed thermal degradation above 240°C. X-ray diffraction (XRD) confirmed almost zero crystallinity for sulfonated PEEK/MMT. When the degree of sulfonation was increased to 80%, ion-exchange capacity, water uptake, and proton conductivity were increased to almost 2.4 meq/g, 75%, and 0.06 S/cm, respectively. Methanol permeability was decreased to 5 × 10-8 cm 2 /s by the addition of 10 wt % MMT. A sulfonated PEEK/MMT membrane with 62% of sulfonation and 1.0 wt % MMT loading showed membrane selectivity of approximately 8500 compare to 4500 of Nafion 117.