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

Rudzani Sigwadi,Touhami Mokrani,Phumlani Msomi,Fulufhelo Nemavhola

doi:10.3390/polym14020263

Rudzani Sigwadi, Touhami Mokrani + Show 2 more

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https://doi.org/10.3390/polym14020263

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Journal: Polymers	Publication Date: Jan 10, 2022
Citations: 13	License type: CC BY 4.0

Affiliation: University of South Africa, University of Johannesburg

Abstract

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.

Highlights

IntroductionAt low to medium temperatures, the introduction of hygroscopic inorganic nanomaterials such as silica, titanium dioxide, zirconium dioxide, and nanoclays into the polymer matrix has improved features of composite membranes such as water retention capacity and ionic conductivity [15]
When the temperature is raised to 80 ◦ C, the results demonstrate that nanocomposite membranes have a lower methanol penetration, indicating that water permeation is greater than methanol permeation at high temperatures
The results revealed that the nanocomposite membranes obtained a lower water contact angle than the commercial Nafion® membrane

Summary

Introduction

At low to medium temperatures, the introduction of hygroscopic inorganic nanomaterials such as silica, titanium dioxide, zirconium dioxide, and nanoclays into the polymer matrix has improved features of composite membranes such as water retention capacity and ionic conductivity [15]. When the amount of filler is increased, it weakens the link between the organic polymer and inorganic filler which causes poor interfacial interaction, resulting in a loss of conductivity [6] When inorganic acid such as sulfated zirconia is calcined at 300 ◦ C, it improves proton conductivity (14.5 mS/cm), with better ion-exchange capacities (IEC) of 0.54 meq/g and greater water uptake due to sulfate ions, which raises the sulfonic acid content inside the membrane [16].

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