(117t) Optimization of the Fuel Cell Interface by Controlled Deposition of Catalyst and Ionomer

Current hydrogen fuel cells are fabricated by using expensive materials in a very inefficient manner. In addition, the structure of the current hydrogen fuel cell utilizes an ill-defined, two-dimensional interface where protons, electrons, and oxygen must all combine to produce water. By using surface-initiated growth of ionomer from catalyst-modified electrode surfaces, materials can be used much more efficiently, allowing for a three-dimensional interface that could improve the power output of the hydrogen fuel cell. In our approach, we first deposit an atomic layer of platinum by electroless deposition to replace a copper adlayer on a gold cathode, and then we grow a fluorocarbon, proton-conducting polymer film by ring opening metathesis polymerization and subsequent sulfonation. Key advantages of this approach are the extremely low Pt loadings, high Pt utilization, and the chemical anchoring of the ionomer to the catalyst surface without negatively impacting the performance of the Pt catalyst. This last feature is achieved by growing the ionomer from the surface and then electrochemically desorbing from the surface adsorbates that are not linked to ionomer. The combined fluorocarbon and sulfonate structuring within the film improves the current and potential of the oxygen reduction reaction by providing hydrophobic domains for oxygen transfer as well as pathways for proton conduction to the electrode/catalyst surface. Characterization methods (infrared spectroscopy, nuclear magnetic resonance, and cyclic voltametry) show promising results.