ABSTRACT
Molten carbonate fuel cells have been commercialized as a mature technology. Due to the liquid electrolyte in molten carbonate fuel cells, gas seal and low contact resistance are easier to achieve than in other fuel cells. Herein, we report an investigation of the viability of a molten oxoacid salt as a novel type of fuel cell electrolyte. In comparison with molten carbonate electrolytes for MCFCs that operate at 500-700 °C, for which a ceramic support matrix is required, the molten proton conductor electrolyte has a lower working temperature range of 150-250 °C. The present study has shown that an electrolyte membrane, in which molten CsH5(PO4)2 is held in a matrix made of PBI polymer and SiO2 powder, has excellent thermal stability, good mechanical properties, and high proton conductivity. In addition, a molten proton conductor fuel cell equipped with such an electrolyte membrane operating at 200 °C showed an open-circuit voltage of 1.08 V, and a stable output voltage during continuous measurement for 150 h at a constant output current density of 100 mA cm-2.
ABSTRACT
[This corrects the article DOI: 10.1039/C7RA12803G.].
ABSTRACT
Electrochemical impedance spectroscopy (EIS) was used to study the polymer electrolyte membrane fuel cells (PEMFC) performance when using single wall carbon nanohorns (SWNH) to support Pt nanoparticles. Additionally, as-prepared and oxidized SWNH Pt-supports were compared with conventional carbon black. Two different oxidizing treatments were considered: oxygen flow at 500 degrees C and reflux in an acid solution at 85 degrees C. Both oxidizing treatments increased SWNH surface area; oxygen treatment increased surface area 4 times while acid treatment increased 2.6 times. The increase in surface area should be related to the opening access to the inner tube of SWNH. Acid treatment of SWNH increased chemical fragility and decreased electrocatalyst load in comparison with as-prepared SWNH. On the other hand, the oxygen treated SWNH sample allowed to obtain the highest electrocatalyst load. The use of as-prepared and oxygen treated SWNH showed in both cases catalytic activities 60% higher than using conventional carbon black as electrocatalyst support in PEMFC. Moreover, EIS analysis indicated that the major improvement in performance is related to the cathode kinetics in the as-prepared SWNH sample, while concerning the oxidized SWNH sample, the improvements are related to the electrokinetics in both anode and cathode electrodes. These improvements should be related with differences in the hydrophobic character between SWNH and carbon black.
