Preparation and characterization of bifunctional graphitized carbon-supported Pt composite electrode for unitized regenerative fuel cell

A bifunctional graphitized carbon-supported Pt oxygen electrode with montmorillonite-assisted dispersion was synthesized using an ultrasonic mixed technique process. By comparison, the graphitized carbon-supports obtain the optimal crystal quality with decreasing I-D/I-G ratio from 1.43 to 0.81 and narrow the peak linewidth from 186 to 84 cm(-1). Both Raman and the selected area diffraction analysis illustrate that the amorphous carbon tends to decrease via high-temperature graphite annealing so that the number of active C atoms will be reduced to improve oxidation resistance. From the CV measurements, the 20 wt.% Pt/graphite produces the highest specific charge transfer due to helpful montmorillonite assisted dispersion, whereas Pt size can only aggregate to grow bigger with an increase the Pt/graphite concentration. The polarization test of URFC presents the optimal performance in both the water electrolysis and fuel cell modes, with cell potentials of 1.6 V and 0.6 Vat 100 mA cm(-2), respectively; it exhibits an optimized energy conversion efficiency of 37.5%, which is better than a Pt/C electrocatalyst-coated membrane due to its having more mass transportation formation and corrosion suppression. By using generated hydrogen to produce electricity, the total energy transfer efficiency of the cell measurement system will reach 50.6%. (C) 2011 Elsevier B.V. All rights reserved.