Nonstoichiometric cerium oxide (CeOx) nanomaterials are considered the most efficient radical scavengers with regenerative redox behavior and are emerging as a pivotal ingredient to secure long-lasting energy conversion devices. However, the environment of energy conversion reactions, which hampers a regeneration of Ce chemical states and severely degrades CeOx antioxidation efficiency, engenders the thirst for CeOx surface passivation strategies that confer high colloidal stability, robust chemical durability, and efficient radical scavenging performance. Here, as a proof-of-concept study, we suggest that chemically durable mesoporous silica (mSiO2) shells with high colloidal stability in polar media boost CeOx antioxidation efficiency. The mSiO2 enabled the even dispersion of the CeOx nanoparticles (NPs) in polar media, effectively mitigated radical scavenging activity degradation, and an increased ratio of highly active Ce(III) states. Importantly, a proton exchange membrane (PEM) based on the CeOx/mSiO2 core/shell exhibited a much lower disintegration rate during the Fenton's test than the CeOx-based PEM and the pristine one. Furthermore, in fuel cell tests, the CeOx/mSiO2-based PEM demonstrated excellent durability preserving 91.7% of initial maximum power density after 100 h-durability tests, while other PEMs underwent drastic performance degradation. In addition, systematic modulation of structural factors in CeOx/mSiO2 allowed demonstrating the multifunctionality of the mSiO2 shell.
Bibliographical noteFunding Information:
This work was supported by the KIST Institutional Program ( 2E31002 ), Research Programs (NRF-2020M3H4A3081817 and NRF-2021M3I3A108287911) of National Research Foundation of Korea funded by Ministry of Science and ICT, and the Industrial Strategic Technology Development Program ( 20011712 ) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea).
© 2021 Elsevier B.V.
- Cerium oxide
- Polymer electrolyte membrane fuel cells
- Reinforced composite membranes
- Surface passivation
ASJC Scopus subject areas
- General Chemistry
- Environmental Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering