Effect of heat treatment of electrodes on direct borohydride-hydrogen peroxide fuel cell performance

Abstract

This work investigates the effect of heat treatment of electrodes on the performance of a direct borohydride-hydrogen peroxide fuel cell (DBPFC). The electrodes are prepared by direct deposition of catalyst onto the surface of a micro porous layer (MPL) supported by a backing layer. The MPL is composed of multi-walled carbon nanotubes (MWCNT) while the backing layer is made of carbon cloth. Palladium and gold are sputter-deposited as anode and cathode catalysts, respectively. After heat treating electrodes at 400 degrees C in air atmosphere, the maximum power density of the DBPFC is significantly improved from 113 to 267 mW cm(-2) at 25 degrees C. Long-term DBPFC performance is improved as well. The apparent improvement of the performance is due to the enhanced hydrophilic nature of catalyst layers as a consequence of heat treatment so that the utilization of catalysts is improved. The hydrophilic nature of the electrodes is from the decrease in concentration of hydrophobic fluorocarbon groups in the catalyst layers. Although heat treatment involves minor disruption of catalysts, the transition of water affinity in the catalyst layers far outweighed its influence which was demonstrated by the improved DBPFC performance.