Zirconia based /Nafion coposite membranes for fuel cell applications

The nanoparticles of zirconium oxide, sulfated and phosphated zirconia were used to modify a Nafion membrane in order to improve its water retention, thermal stability, proton conductivity and methanol permeability so that it can be used at higher temperatures in fuel cell. These modified Nafion nanocomposite membrane with inorganic nanoparticles have been designed to run at operating temperatures between 120 oC and 140 oC because higher temperature operation reduces the impact of carbon monoxide poisoning, allows attainment of high power density and reduces cathode flooding as water is produced as vapor. The inorganic nanoparticles were incorporated within the Nafion matrix by recast, ion exchange and impregnation methods. The membrane properties were determined by ion exchange capacity (IEC), water uptake, methanol permeability and proton conductivity. The characterization of the inorganic nanoparticles within the nanocomposite membranes was determined by X-Ray diffraction (XRD), Brunau-Emmett-Teller (BET) surface area and Fourier transform infrared spectroscopy (FTIR) for structural properties. Thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) were used to determine the thermal properties, and the morphological properties were probed by Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). Pristine ZrO2, sulfated and phosphated ZrO2 nanoparticles were synthesized successfully. The particle sizes ranged from 30 nm to 10 nm respectively. The resulted particles were incorporated to a Nafion membrane with good dispersity. The conductivity of the nanocomposite membrane were around 0.1037 S/cm at 25 oC with a higher water uptake of 42 %. These results were confirmed by the highest IEC value of 1.42 meg.g-1 of Nafion/ S-ZrO2 nanocomposites membrane. These high IEC value may due to the incorporation of superacid S-ZrO2 nanoparticles which increased the membrane acid property for providing new strong acid site.Chemical EngineeringM. Tech. (Chemical Engineering

Preparation of a high surface area zirconium oxide for fuel cell application

Abstract Stable and high surface area zirconium oxide nanoparticles have been synthesised by means of the hydrothermal method. The Brunauer–Emmett–Teller results show that a high surface area of 543 m2/g was obtained in the hydrothermal process, having a high porosity in nanometre range. The hydrothermal method was applied at 120 °C by using an autoclave with a Teflon liner at an ambient pressure for 48 h. High-resolution scanning electron microscopy shows the different morphologies of zirconia nanoparticles, which could be categorised as one-dimensional and zero-dimensional, as they had a high crystallite orientation, which was also confirmed by the X-ray diffraction (XRD). The mixture of two types of cubic phases in one sample was obtained from XRD and confirmed by the zirconia nanostructure, showing the stable phase of fluorite, which has full cubic symmetry (Im-3m), and also an Arkelite zirconia nanostructure, showing the stable phase of fluorite, which has full cubic symmetry (Fm-3m). The XRD results also show the different structure orientations of face-centred cubic and body-centred cubic in one sample

Synthesis of zirconia-based solid acid nanoparticles for fuel cell application

Zirconia nanoparticles were prepared by the precipitation and ageing methods. The precipitation method was performed by adding ammonium solution to the aqueous solution of zirconium chloride at room temperature. The ageing method was performed by leaving the precipitate formed in the mother liquor in the glass beaker for 48 hours at ambient temperatures. The nanoparticles from both methods were further sulphated and phosphated to increase their acid sites. The materials prepared were characterised by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Brunauer-EmmettTeller (BET), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The XRD results showed that the nanoparticles prepared by the precipitation method contained mixed phases of tetragonal and monoclinic phases, whereas the nanoparticles prepared by ageing method had only tetragonal phase. The TEM results showed that phosphated and sulphated zirconia nanoparticles obtained from the ageing method had a smaller particle size (10–12 nm) than the nanoparticles of approximately 25–30 nm prepared by precipitation only. The BET results showed that the ZrO2 nanoparticles surface area increased from 32 to 72 m2/g when aged

Zirconia, Sulphated Zirconia and Zirconium Phosphates as additives for membranes in PEM Fuel Cell

This research investigates the impact of zirconia nanoparticle in conductivity, water uptake, fuel crossover and fuel efficiency of modified Nafion® membranes. Synthesized water-retaining mesoporous zirconia nanoparticles (ZrO2) were used to modify Nafion® membrane in order to enhance the thermal properties, water uptake, proton conductivity and mechanical strength of composited membrane for fuel cell applications. Recast and impregnation methods were used to prepare a nanocomposite membrane with required weight% of zirconia nanoparticles. The mechanical stability of modified membranes has become a priority for fuel cell applications as the membranes must endure all the fuel cell operations (to prevent crossover of the fuel while still conducting). Their mechanical stress and yielding stress in the recast and impregnation methods compared with the commercial Nafion® membrane were observed under tensile tests. The incorporated membrane with zirconia nanofiller shows an improvement in mechanical strength, due to the hydrophilic phase domains in the nanocomposite membrane. The water contact angle and water uptake of the composited membrane were measured. The modified membranes with zirconia nanoparticles showed a significant improvement in water uptake and contact angle leading to enhanced hydrophilicity when compared to unmodified hydrophobic Nafion® membrane. This shows the potential for use as electrolytes in fuel cell applications. Zirconia nanoparticles were further impregnated with sulfuric acid and phosphoric acid to introduce the additional acid sites for absorption of water. In addition, zirconium phosphates (ZrP) and sulfated zirconia (S-ZrO2) were incorporated into Nafion® 117 membrane by impregnation method to obtain a reduced methanol permeation and improved proton conductivity for fuel cell application. The mechanical properties and water uptake of Nafion® membrane incorporated with zirconium phosphates and sulfonated zirconia nanoparticles were much more improved when compared to the commercial Nafion® 117, due to the presence of acid site within the nanoparticles. Furthermore, the results showed that incorporating ZrP and S-ZrO2 nanoparticles enhanced proton conductivity and IEC of modified Nafion ® membrane as they sustain water affinity and strong acidity. The results show that nanocomposite membranes have low water content angle, improved thermal degradation, higher conductivity and lower methanol permeability than commercial Nafion® 117 membrane, which holds great promise for fuel cell application. The Nafion®/ sulfated zirconia nanocomposite membrane obtained a higher IEC and water uptake due to the presence of SO 2-4 providing extra acid sites for water diffusion. To reduce the agglomeration of ZrO2 nanoparticles and improve the water diffusion, ZrO2 was electrospun with polyacrylonitrile (PAN) solution to obtain a 1D morphology. The recast method was used to synthesize the high thermal and mechanical stability of Nafion® membrane incorporated with polyacrylonitrile (PAN) nanofibers. The modified Nafion® membranes exhibited improved fuel cell efficiency when tested in direct methanol fuel cells with a high proton conductivity due to incorporating PAN/Zr nanofibers that retain water within the membrane. Moreover, nanocomposite membranes achieved a reduced methanol crossover of 4.37 x 10-7 cm2 /s (Nafion®-PAN/ZrP nanofibers), 9.58 x 10-8 cm2 /s (Nafion®- PAN/ZrGO nanofibers) and 5.47 x 10-8 cm2 /s (Nafion®-PAN/Zr nanofibers), which is higher than 9.12 x 10-7 cm2 /s of recast Nafion® membrane at the higher concentration of 5M. All the blended membranes showed increase in power density at a temperature of 25 °C in comparison with pristine recast Nafion® membrane (76 mW·cm−2 , 69 mW·cm−2 , 44 mW·cm−2 , 18 mW·cm−2 ). Finally, incorporating electrospun PAN/ Zr nanofibers into Nafion® membrane has successfully reduced the use of Nafion® solution that will eliminate the cost problems, while improves the protons conductivity and the methanol permeability which influence the fuel cell efficiency and long-term stability.Physic

The Effect of Sulfated Zirconia and Zirconium Phosphate Nanocomposite Membranes on Fuel-Cell Efficiency

To investigate the effect of acidic nanoparticles on proton conductivity, permeability, and fuel-cell performance, a commercial Nafion® 117 membrane was impregnated with zirconium phosphates (ZrP) and sulfated zirconium (S-ZrO2) nanoparticles. As they are more stable than other solid superacids, sulfated metal oxides have been the subject of intensive research. Meanwhile, hydrophilic, proton-conducting inorganic acids such as zirconium phosphate (ZrP) have been used to modify the Nafion® membrane due to their hydrophilic nature, proton-conducting material, very low toxicity, low cost, and stability in a hydrogen/oxygen atmosphere. A tensile test, water uptake, methanol crossover, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) were used to assess the capacity of nanocomposite membranes to function in a fuel cell. The modified Nafion® membrane had a higher water uptake and a lower water content angle than the commercial Nafion® 117 membrane, indicating that it has a greater impact on conductivity. Under strain rates of 40, 30, and 20 mm/min, the nanocomposite membranes demonstrated more stable thermal deterioration and higher mechanical strength, which offers tremendous promise for fuel-cell applications. When compared to 0.113 S/cm and 0.013 S/cm, respectively, of commercial Nafion® 117 and Nafion® ZrP membranes, the modified Nafion® membrane with ammonia sulphate acid had the highest proton conductivity of 7.891 S/cm. When tested using a direct single-cell methanol fuel cell, it also had the highest power density of 183 mW cm−2 which is better than commercial Nafion® 117 and Nafion® ZrP membranes

Dataset from the uniaxial tensile testing of human curly hair fibers under different conditions

Individual human hair fibers exhibiting a curly morphology were procured from a female donor within her early thirties (30s). The selected hair fibers donor had refrained from undergoing any form of chemical treatment, including dyeing, relaxing, and bleaching, for a minimum period of six (6) months prior to specimen collection. The isolated single fibers were subjected to uniaxial tensile testing at various strain rates (100.s−1,10−2. s−1 10−3. & 10−4.s−1). Furthermore, the specimens underwent testing under dry conditions at a temperature of 25°C, as well as full immersion in a saline solution at both 25°C and 35°C. The ensuing mechanical attributes, encompassing engineering was analyzed following the tensile testing