Nafion®/ sulfated zirconia oxide-nanocomposite membrane: the effects of ammonia sulfate on fuel permeability
Nafion®/sulfated zirconium nanocomposite membranes were prepared by incorporating sulfonated zirconia with ammonia sulfate and sulphuric acid, which enhances proton conductivity and reduces fuel crossover on Nafion® membrane as they sustain water affinity and strong acidity. XRD, AFM, SEM, FTIR and TGA were used to investigate the morphology and high temperature degradation of nanocomposite membranes compared with commercial Nafion® 117 membrane. The results show that nanocomposite membranes have low water content angle, improved thermal degradation and higher conductivity 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 SO42− providing extra acid sites for water diffusion. The proton conductivity calculated from impedance spectroscopy measurements were 7.891 S/cm and 0.146 S/cm, respectively, when compared with 0.113 S/cm of commercial Nafion® 117 membrane. The Nafion®/sulfated zirconium nanocomposite membranes showed a highest power density of 183 m. cm−2 when evaluated using a direct single cell methanol fuel cell.
KeywordsAmmonia sulfate Fuel cell Proton conductivity Polymer composite Nafion membrane
The authors would like to acknowledge and thank the National Research Foundation of South Africa (NRF) and University of South Africa (AQIP) for their financial support. We are also thankful to the CSIR and University of Johannesburg for analysis and performance studies.
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