| The high cost of cathode catalyst due to the large amount of platinum electrocatalyst used for Oxygen Reduction Reaction (ORR) is one of the major impediments to the commercialization of the fuel cell. The objective of this dissertation is to develop Pt-free electrocatalysts for PEM fuel cell cathodes as alternatives to the existing Pt-based catalysts.; A novel method was developed to synthesize ruthenium-based chelate (RuN x/C) and bimetallic electrocatalysts (MeRuNx/C) for the oxygen reduction reaction. To optimize the performance of the catalyst, the activity of the catalysts was studied as a function of pyrolysis temperature, particle size, the nitrogen content and surface modification of the catalyst. The catalysts were screened using the rotating ring disk electrode (RRDE) technique. High-temperature pyrolysis was studied to investigate the formation of the catalytic sites. It was found that the presence of nitrogen in the catalyst matrix improves the catalytic activity and selectivity toward four-electron reduction of oxygen to water. The RuNx/C and RuFeNx/C catalyst modified in the presence of surface active materials exhibited comparable catalytic activity and selectivity to the 20 wt. % commercial Pt/C catalyst in acidic media. The intensive study on RuCoNx/C and RuFeNx/C revealed the synergistic effect between Ru and transition metals. A methodology was developed in which the transition metal particles are encapsulated by graphitic carbon during the pyrolysis process which improves the stability of the catalysts. |
