Impact of CeO<sub>2</sub> Nanoparticle Morphology: Radical Scavenging within the Polymer Electrolyte Membrane Fuel Cell
Yejin Yun, Aniket Kumar, Jaewoon Hong, Sun‐Ju Song
Abstract
This paper reports a systematic investigation of the radical scavenging behaviour of ceria with different morphological shapes inside Nafion membrane. All the ceria nanostructure is synthesized using a template-free hydrothermal route. Distinct crystal planes of CeO 2 have different numbers of broken bonds and reaction sites having different surface energies. So, the preparation of CeO 2 with various uncovered planes may enhance its scavenging activity. The crystal structure, morphology, and lattice structure are investigated using transmission electron microscopy (TEM), and x-ray diffraction (XRD). The results show that the radical scavenging efficiency of ceria strongly depends on the active surface plane, and decreases in the following order: nanorods > nanocube > nanosphere. Furthermore, the concentrations of surface oxygen vacancies and lattice cerium (III) are correlated with the morphology of the nanoparticles. This relationship clarifies the vital scavenging mechanism of CeO 2 that mitigates degradation inside the polymer electrolyte membrane. This is because the inherent lattice strain on the active planes of nanosized ceria with different shapes affects their surficial reactions. The existence of prominent concentration of oxygen vacancy in the nanometric dimension of ceria leading to greater Ce 3+ generation by exposed active phase CeO 2 nanoparticles is key to achieve a durable hybrid Nafion membrane.