Physical Chemistry Research Toward Proton Exchange Membrane Fuel Cell Advancement.

Hydrogen fuel cells, the most common type of which are proton exchange membrane fuel cells (PEMFCs), are on a rapid path to commercialization. We credit physical chemistry research in oxygen reduction electrocatalysis and theory with significant breakthroughs, enabling more cost-effective fuel cells. However, most of the physical chemistry has been restricted to studies of platinum and related alloys. More work is needed to better understand electrocatalysts generally in terms of properties and characterization. While the advent of such highly active catalysts will enable smaller, less expensive, and more powerful stacks, they will require better understanding and a complete restructuring of the diffusion media in PEMFCs to facilitate faster transport of the reactants (O2) and products (H2O). Even Ohmic losses between materials become more important at high power. Such lessons from PEMFC research are relevant to other electrochemical conversion systems, including Li-air batteries and flow batteries.