Mesoporous Silica‐Stabilized Ceria Antioxidants for Enhancing PEMFC Durability

Enhancing the durability of polymer electrolyte membrane fuel cells (PEMFCs) is critical for advancing a hydrogen‐powered clean energy future. A major obstacle to improving PEMFC durability is reactive oxygen species (ROS) that deteriorate PEMFC performance by oxidizing membrane electrode assembly (MEA). While CeO x ‐based nanomaterials are widely used as antioxidants, they often undergo decline in efficacy by their nanostructure deformation, hampering stable PEMFC operation. Here, mesoporous silica nanoparticles (MSNs) are reported as a stabilizer for antioxidants, effectively alleviating the CeO x disintegration. MSNs facilitate the formation of uniformly dispersed CeO x nanoparticles smaller than 2 nm having abundant oxygen vacancies and high proportion of Ce(III) oxidation states. The well‐defined mesoporous structure of MSNs effectively confines CeO x in the internal voids and prevents CeO x agglomeration, thereby exhibiting sustained antioxidation efficacy within the Pt/C‐based electrodes. Importantly, CeO x /MSN mitigates the MEA degradation, retaining 95% of PEMFC performance even after 100 h durability tests under the ROS‐rich environment.