Iron-Nitrogen-Carbon Catalysts for Proton Exchange Membrane Fuel Cells

Fuel cell technology is on its verge of deployment as one of the solutions for decarbonization of transportation. It currently uses platinum-based catalysts, being the largest materials cost factor, subject to market volatility, limited availability, and unfavorable geopolitical source location. Hence, Earth-abundant elements-based materials, and among those, platinum-free catalysts, could be an ultimate solution. Among several such catalysts, the transition-metal nitrogen-carbon ones have shown adequate activity and promise in durability, the latest being the most vulnerable treat. Recent years have seen initial successes in incorporation of iron-nitrogen-carbon catalysts in fuel cells and their evaluation under automotive relevant conditions. The catalysts can be described as N-doped, graphene-like carbonaceous materials, with transition metal atomically dispersed and associated with the pyridinic nitrogen-containing in-plane or edge defects in graphene. Here, we provide a view on these materials' chemical composition and morphology that provide for the reactivity and stability of transition-metal-containing active sites.