Search

Abstract: The scope of the present work was to investigate and evaluate the electrochemical activity of H2/O2 fuel cells based on the influence of a heteropolyacid glass membrane with a Pt/C electrode at low temperature. A new trend of sol–gel derived PMA (H3PMo12O40) heteropolyacid-containing glass membranes inherent of a high proton conductivity and mechanical stability, was heat treated at 600°C and implemented to H2/O2 fuel cell activities through electrochemical characterization. Significant research has been focused on the development of H2/O2 fuel cells using optimization of heteropolyacid glasses as electrolytes with Pt/C electrodes at 30°C. A maximum power density of 23.9mW/cm2 was attained for operation with hydrogen and oxygen, respectively, at 30°C and 30% humidity with the PMA glass membranes (4–92–4mol%). Impedance spectroscopy measurements were performed on a total ohmic cell resistance of a membrane-electrode-assembly (MEA) at the end of the experiment. [Copyright &y& Elsevier]

Abstract: A new class of proton conducting glass membranes for hydrogen fuel cell applications are being developed using phosphotungstic acid. These glasses are being design to yield high proton conductivities could be potential substitutes for electrolytes in H2/O2 fuel cell. P2O5–SiO2–PWA glasses have been non-crystalline phases confirmed by structural studies. The glass materials showed good mechanical and thermal stability, and also found a maximum proton conductivity of 9.1×10−2 S/cm at 90°C and 30% RH. The average pore size less than 5nm was determined by Barrett–Joyner–Halenda (BJH) desorption method. The electrochemical activity was investigated by polarization curves and current–voltage profiles. A maximum power density value of 10.2mW/cm2 was obtained using 0.15mg/cm2 of Pt/C loaded on electrode and 5P2O5–87SiO2–8PWA glasses at 30°C and 30% humidity. [Copyright &y& Elsevier]

Abstract: Proton conductivity was examined in P2O5–ZrO2–SiO2 glasses prepared by sol–gel method and characterized for structural, nitrogen adsorption–desorption and thermal measurements. The amorphous phases of our glasses were confirmed by X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy studies identified the presence of Sih name="sbnd" />Si and Zrh name="sbnd" />Si bond structures on glass surface. The differential thermal analysis and thermal gravimetric analysis (TGA/DTA) results showed decomposition in the temperature range from 40 to 300°C. A distribution of average pore size 2.5nm, pore volume 0.26cm3 g−1 and surface area 407m2 g−1 were obtained by pore analysis. Proton conductivities of all samples (thickness 0.5–1mm) increased with an increase in relative humidity (RH) (40–90%), indicating that continuous paths suitable for proton conduction were formed in the glasses heat treated at 600°C due to the adsorption of water. The temperature dependence of the conductivity for all compositions increases with increasing temperature range of 30–90°C at relative humidity 70%. An open circuit potential of ∼1V and a maximum power density of about 0.9mWcm−2 were achieved at 30°C with relative humidity 30%. [Copyright &y& Elsevier]

Abstract: P2O5–TiO2–SiO2 based glasses have been prepared by a sol–gel process. The glasses were characterized by structural, thermal, nitrogen adsorption–desorption and conductivity measurements. The structural formation has been confirmed by the FTIR and NMR analysis. The proton conductivity of the glasses increased linearly with increase in temperature. Glasses with an average pore size less than 2nm showed higher values of proton conductivity in humid atmosphere. The conductivity value increased from 6.47×10−4 S/cm to 3.04×10−2 S/cm at 70% RH in the temperature range 30–90°C. We observed in fuel cell measurements that the performance of the E1 electrode is superior to that of the other electrodes at the same operating condition. The power density shows a similar pattern to current density. [Copyright &y& Elsevier]

Abstract: In order to investigate the applicability of the galvanostatic reduction of uranium(VI) to U(IV) in the electrolytic reduction and ion exchange (ERIX) Process, a novel aqueous reprocessing technique for spent mixed uranium and plutonium oxide (MOX) fuels for fast-breeder reactors (FBR), an improved electrolytic cell was developed and fundamental electrolytic properties were examined using U and some fission products (FPs) in HNO3 media. As the result of the electrolysis for a 200cm3 solution of 0.5M (M=mol/dm3) U(VI), 6M HNO3, and 0.5M N2H4, it was found that more than 99% of U(VI) was reduced to U(IV) before the shift to the side reaction when the initial constant current supplied was no higher than 10A. It was also found that the reduction of U(VI) to U(IV) was achieved using the cell under coexistence with the FPs, e.g. noble metals, which are easily deposited by the electrolytic reduction. [Copyright &y& Elsevier]

Abstract: Proton conducting membranes for hydrogen fuel cell applications are being developed using sol–gel-derived P2O5-TiO2-SiO2 glasses. The present work is devoted to the structural analysis of P2O5-TiO2-SiO2 glasses containing controlled pore sizes and the surface area of the glasses reaching a maximum 410m2/g, while the average pore diameter is about 2.4nm. They were characterized by nitrogen adsorption–desorption measurements, thermal measurement as well as FTIR spectroscopy. The structural studies were based on the evolution of the intensities and profiles of certain characteristics bands in the FTIR spectra. In order to increase proton conductivity at low relative humidity, the result suggests that the mobility of proton in the P2O5-TiO2-SiO2 glasses increases with decreasing O strength. An H2/O2 fuel cell was constructed using the P2O5-TiO2-SiO2 glasses as electrolyte and Pt/C-loaded carbon paper sheets as electrodes. Results show that the performance of the cell is an output power of 88μW/cm2 at 30°C with humidity. [Copyright &y& Elsevier]

Abstract: The H2/O2 fuel cell based on the proton conducting P2O5–ZrO2–SiO2 glasses was prepared by sol–gel technique. Structural characterization were carried out using X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (31P MAS NMR), N2 adsorption–desorption analysis, differential thermal analysis (DTA) and thermal gravimetric analysis (TGA) and impedance measurements. The absorption bonds of Si–O–Si, Si–O–P and Si–O–Zr were observed in the P2O5–ZrO2–SiO2 glasses which were heat treated at 600°C. A sample (5P2O5–4ZrO2–91SiO2, mol%) was selected as the electrolyte for the H2/O2 fuel cell test and yielded the maximum power density value of 8.5mW/cm2 using electrochemical measurements at 30°C under relative humidity atmosphere. [Copyright &y& Elsevier]