Final Scientific Report : Development of Transition Metal/ Chalcogen Based Cathode Catalysts for PEM Fuel Cells

摘要

The aim of this project was to investigate the potential for using base metal sulfides and selenides as low cost replacements for precious metal catalysts, such as platinum, currently being used in PEM fuel cells. The approach was to deposit thin films of the materials to be evaluated onto inert electrodes and evaluate their activity for the cathode reaction (oxygen reduction) as well as ex-situ structural and compositional characterization. The most active materials identified are CoS2 and the 50:50 solid solution (Co,Ni)S2. However, the OCP of these materials is still considered too low, at 0.83V and 0.89V vs. RHE respectively, for testing in fuel cells. The methods employed here were necessary to compare with the activity of platinum as, when nano-dispersed on carbon supports, the active surface area of these materials is difficult to measure, making comparisons inaccurate. This research adds to the knowledge of potential candidates for platinum replacement in order to reduce the cost of PEM fuel cell technology and promote commercialization. Although the fabrication methods employed here are strictly experimental, methods were also developed to produce nano-dispersed catalysts with similar compositions, structure and activity. Cycling of these catalysts to highly oxidizing potentials resulted in an increase of the open circuit voltage to approach that of platinum, however, it proved difficult to determine why using these dispersed materials. The potential for non-precious, non-metallic, low cost, compound catalysts for PEM fuel cells has been investigated and demonstrated.