Recent advances in ceria-based free radical scavenging nanoparticles for durability enhancement of polymer electrolyte membrane fuel cells

Abstract

Research on polymer electrolyte membrane fuel cells (PEMFCs) has received great attention over the past few decades, leading to substantial advancements in their performance. However, their susceptibility to chemical degradation during the operation remains a great challenge, diminishing overall device longevity. This degradation is largely due to the unintended generation of reactive oxygen species (ROS), including free radicals, which break down the membrane polymers and catalyst layers. To address this issue, the incorporation of radical-scavenging additives has emerged as a promising strategy, as these materials can effectively react with ROS through various redox reactions. In particular, defective ceria (CeO_2−x) has shown great potential as a ROS scavenger in PEMFC devices due to its fast ROS scavenging reaction kinetics via reversible redox cycling between Ce³⁺/Ce⁴⁺ through oxygen vacancy formation and annihilation. This review highlights recent advancements in surface engineering strategies to improve the radical scavenging performance and surface regeneration kinetics of CeO_2−x-based additives. Furthermore, this review provides insights into developing highly active and stable radical scavenger additives, thereby enhancing the overall chemical stability of the PEMFC devices and paving the way for future research directions.