Atomically Dispersed Fe Doping in Co@CoO/NC Core-Shell Hybrids as Efficient Four-Electron Oxygen Reduction and...

Nonprecious metal oxygen reduction reaction (ORR) electrocatalysts have garnered increasing attention owing to their extremely low cost compared with Pt-based electrocatalysts. However, realizing the four-electron pathway and developing highly antipoisoning nonprecious metal ORR electrocatalysts are key challenges in practical energy devices. Herein, atomic-level Fe doping was applied to Co@CoO core-shell nanoparticles anchored in a porous carbon-nitrogen framework (denoted Fe-Co@CoO/NC) derived from FeCoZn metal-organic frameworks. The Fe-Co@CoO/NC exhibits a half-wave potential of 0.895 V in an alkaline medium, superior to that of commercial Pt/C (0.842 V), and high in situ methanol and CO tolerance. In situ spectroscopic characterizations and Rotating Ring-Disc Electrode (RRDE) investigations reveal that four-electron ORR is achieved using Fe-Co@CoO/NC through O-O bond breaking in OOH* intermediate species. In addition, density functional theory calculations show that compared with Pt, Fe-CoO effectively suppresses H2O2 generation and favors a more advantageous four-electron reaction pathway. Fe-Co@CoO/NC as a cathode material for direct methanol fuel cells (DMFCs) reaches a peak power density of 113.7 mW·cm-2, markedly outperforming commercial Pt/C (72.0 mW·cm-2). This work provides an effective strategy for preparing high-efficiency nonprecious metal four-electron ORR catalysts with intrinsic tolerance to methanol and CO for DMFC devices.