Atomic bridging of Tellurium to Regulate Fe Diatomic Coordination for Efficient Oxygen Electrocatalysis

Abstract

Fe–N–C electrocatalysts exhibit enhanced performance in the oxygen reduction reaction (ORR) due to their unique metal–nitrogen coordination structure on the carbon support, but suboptimal coordination and insufficient stability limit their performance. Herein, an Fe–Te diatomic site electrocatalyst with axial coordination (Fe₂Te₂/NC) was developed to modulate the microenvironment of Fe diatomic sites on carbon support through atomic bridging with Te. This design significantly enhances both the electrocatalytic activity and long-term durability for ORR. Theoretical calculations reveal that the Fe–Te interactions within the diatomic sites increase electron density around Fe centers, thus enhancing oxygen adsorption and lowering the energy barrier for the rate-determining step in oxygen reduction. Partial density of states analysis further reveals that the d-band center of Fe₂Te₂/NC is closer to the Fermi level, providing more unoccupied orbitals for the adsorption of oxygen molecules at Fe sites. Indeed, electrochemical testing confirms that the Fe₂Te₂/NC catalyst has good ORR activity, achieving a half-wave potential of 0.89 V and enhanced stability, surpassing the commercial Pt/C catalyst. Furthermore, a rechargeable zinc-air battery assembled with this catalyst in an aqueous electrolyte demonstrated a high power density of 380.7 mW cm^–2 and maintained stable discharge operation for over 1100 h.