Atomically Dispersed Metal Catalysts for Oxygen Reduction

The unprecedented oxygen reduction reaction (ORR) activity of atomically dispersed and nitrogen coordinated metal site (e.g., Fe, Co, or Mn) catalysts makes them promising low-cost candidates to replace platinum group metal (PGM) catalysts in proton exchange membrane fuel cells (PEMFCs). This Perspective focuses on emerging developments in mechanistic understanding, innovative synthetic concept, and performance improvement of these high-risk, high-reward PGM-free catalysts. Starting from theoretical and computational analysis of active sites and ORR pathways, we provide a concise overview of recent progress in catalyst synthesis, characterization, and catalytic performance with an aim to elucidate structure property correlations. We also examine remaining challenges and future directions to realize atomically dispersed metal catalysts with sufficient activity and stability for viable PEMFC applications.