Atomically Dispersed Fe Doping in Co@CoO/NC Core–Shell Hybrids as Efficient Four-Electron Oxygen Reduction and Antipoisoning Electrocatalysts for Use in Direct Methanol Fuel Cells

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.