Transition metal carbides as cathode supports for PEM fuel cells

As energy demands increase and environmental issues loom, fuel cells (FCs) have attracted significant attention as an alternative to conventional energy sources. Their use encompasses portable applications, transportation, and a stationary grid-power mainly due to their low-temperature operation and quick start-up. However, the primary challenge is improving fuel cell durability to meet 2025 U.S. Department of Energy targets (e.g., 8,000+ h for automotive drive cycle). Proton exchange membrane fuel cell (PEMFC) catalysts currently suffer from low durability, undermining their wide-scale deployment into the consumer and industrial markets. Platinum group metals (PGMs) are still the most common catalysts used in PEMFCs as they provide among the highest activity for electrode reactions and lifetime stability. An effective way to decrease Pt loading is the adoption of supports to enhance both Pt dispersion and its durability. Corrosion of the carbon-based support was identified to be the major contributor to performance degradation as they suffer from parasitic oxidation to CO₂ (at the cathode). Therefore, there is a significant interest in exploring stable alternatives to replace carbon supports in PEMFCs. Transition metal carbides (TMCs) have attracted significant attention over the last several years as a possible candidate to replace carbon-based catalyst supports in fuel cells. Despite these advantages over carbon supports, the large-scale deployment of TMC-based supports in fuel cells is still hindered by concerns of durability at the high potential on the cathode during start-up and shutdown operation. Here, we address the most relevant studies concerning TMCs as supports for acidic oxygen reduction reaction (ORR) catalysis, including viewpoints about the surface and bulk design of the support, as well as the design of the catalyst itself to enhance the interaction and dispersion with the support.