Multi-function core-shell nanoparticles outperform single-phase counterparts for efficient single-atom catalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Single-atom catalysis (SAC) utilizing nanoparticles (NPs) shows promise but is limited by single-phase materials and suboptimal efficiency.
• Current NP designs often face challenges with stability and limited functional scope in catalytic applications.

Purpose of the Study:

• To develop and investigate core-shell Fe@Fe3O4 nanoparticles as advanced catalysts for enhanced single-atom catalysis.
• To elucidate the catalytic mechanisms and performance improvements offered by the Fe@Fe3O4 core-shell structure in oxygen reduction reactions (ORR).

Main Methods:

• Operando spectroscopy, kinetic isotope effect (KIE) studies, local pH measurements, and density functional theory (DFT) calculations were employed.
• Electrochemical performance was evaluated using half-wave potential (E1/2) measurements and long-term cycling stability tests.
• Device-level testing was conducted in zinc-air batteries.

Main Results:

• The Fe@Fe3O4 core-shell NPs demonstrated superior ORR activity with an E1/2 of 0.952 V vs. RHE, surpassing commercial Pt/C (0.844 V RHE) and Fe single-atom NPs (0.919 V RHE).
• The core-shell structure facilitated weakened *OH adsorption, promoted water dissociation, and enabled tandem proton transfer, contributing to enhanced catalytic performance.
• Exceptional durability was observed, with negligible performance loss after 50,000 potential cycles, attributed to the protective Fe3O4 shell.
• Zinc-air batteries utilizing these catalysts achieved a peak power density of 250.2 mW cm-2 and stable operation over 10,000 cycles.

Conclusions:

• Core-shell Fe@Fe3O4 NPs represent a significant advancement in SAC, offering enhanced catalytic activity and durability.
• The synergistic effect of the Fe@Fe3O4 structure provides a new strategy for designing efficient electrocatalysts.
• This work offers critical insights into NP-mediated catalytic mechanisms and their application in energy storage devices like zinc-air batteries.