Journal of Power Sources, Vol.273, 761-774, 2015
Development of catalytically active and highly stable catalyst supports for polymer electrolyte membrane fuel cells
Novel procedures are developed for the synthesis of highly stable carbon composite catalyst supports (CCCS-800 degrees C and CCCS-1100 degrees C) and an activated carbon composite catalyst support (A-CCCS). These supports are synthesized through: (i) surface modification with acids and inclusion of oxygen groups, (ii) metal-catalyzed pyrolysis, and (iii) chemical leaching to remove excess metal used to dope the support. The procedure results in increasing carbon graphitization and inclusion of non-metallic active sites on the support surface. Catalytic activity of CCCS indicates an onset potential of 0.86 V for the oxygen reduction reaction (ORR) with well-defined kinetic and mass-transfer regions and similar to 2.5% H2O2 production in rotating ring disk electrode (RADE) studies. Support stability studies at 1.2 V constant potential holding for 400 h indicate high stability for the 30% Pt/A-CCCS catalyst with a cell potential loss of 27 mV at 800 rnA cm(-2) under H-2-air, 32% mass activity loss, and 30% ECSA loss. Performance evaluation in polymer electrolyte membrane (PEM) fuel cell shows power densities (rated) of 0.18 and 0.23 g(Pt) kW(-1) for the 30% Pt/A-CCCS and 30% Pt/CCCS-800 degrees C catalysts, respectively. The stabilities of various supports developed in this study are compared with those of a commercial Pt/C catalyst. (C) 2014 Elsevier B.V. All rights reserved.
Keywords:Polymer electrolyte membrane fuel cells;Support stability;Catalyst performance;Potential holding;Electrochemical surface area