Engineering the Local Atomic Environments of Te-Modulated Fe Single-Atom Catalysts for High-Efficiency O₂ Reduction

Atomically dispersed metal-nitrogen-carbon materials (AD-MNCs) are considered the most promising non-precious catalysts for the oxygen reduction reaction (ORR), but it remains a major challenge for simultaneously achieving high intrinsic activity, fast mass transport, and effective utilization of the active sites within a single catalyst. Here, an AD-MNCs consisting of defect-rich Fe-N₃ sites dispersed with axially coordinated Te atoms on porous carbon frameworks (Fe₁Te₁-900) is designed. The local charge densities and energy band structures of the neighboring Fe and Te atoms in FeN₃-Te are rearranged to facilitate the catalytic conversion of the O-intermediates. Meanwhile, the negative shift of the d-band center in FeN₃-Te reduces the energy barrier limit for effective desorption of the final OH^* intermediate. In the electrochemical evaluation, Fe₁Te₁-900 presents a more positive onset potential and half-wave potentials of 1.03 and 0.89 V versus the reversible hydrogen electrode, respectively. Furthermore, the liquid zinc-air batteries assembled with Fe₁Te₁-900 exhibited excellent performances compared to commercial Pt/C. This work opens up new ideas for the development of high-performance ORR electrocatalysts for applications in various energy conversion and storage technologies.