Synergistic Effect of Single Atomic Ce Sites and CeO2 Nanoparticles for Boosting Oxygen Reduction Reaction

Rare-metal Ce-based SACs consisting of single-atomic Ce sites and CeO₂ nanoparticles are constructed by facile gas-phase migration strategy. Moreover, experimental and theoretical analysis demonstrates that the introduction of CeO₂ is beneficial for the decreased energy barrier of the hydrogenation step of ^*OH over the single-atomic Ce sites, which contributes to the enhanced ORR performance.

Abstract

Fe-based single-atomic catalysts (SACs) are considered the most promising non-precious oxygen reduction reaction (ORR) catalysts, whereas further development is largely hindered due to the unavoidable Fenton reaction during the ORR process. Herein rare-metal Ce-based SACs consisting of single-atomic Ce sites and CeO₂ nanoparticles are constructed by a facile gas-phase migration strategy. Theoretical calculation results demonstrate that the synergistic effect of the introduction of CeO₂ and the coordination structure change of single-atomic sites is beneficial for the decreased energy barrier of the hydrogenation step of ^*OH over the single-atomic Ce sites, which contributes to the enhanced ORR performance with positive half-wave potential of 0.88 V in 0.1 m KOH. Moreover, the assembled zinc-air battery can deliver a high power density of 107 mW cm⁻² and remarkable long-term stability of 400 cycles at the current density of 5 mA cm⁻². This work provides a new insight for the design and construction of rare-earth-metal-based SACs for the ORR.