Spin-Selective Coupling in Mott-Schottky Er2 O3 -Co Boosts Electrocatalytic Oxygen Reduction

Abstract

Alkaline oxygen reduction reaction (ORR) is critical to electrochemical energy conversion technology, yet the rational breaking of thermodynamic inhibition for ORR through spin regulation remains a challenge. Herein, a Mott-Schottky catalyst consisting of Er₂ O₃ -Co particles uniformly implanted into carbon nanofibers (Er₂ O₃ -Co/CNF) is designed for enhancing ORR via spin-selective coupling. The optimized Er₂ O₃ -Co/CNF affords a high half-wave potential (0.835 V vs reversible hydrogen electrode, RHE) and onset potential (0.989 V_RHE ) for the ORR surpassing individual Co/CNF and Er₂ O₃ /CNF. Theoretical calculations reveal the introduction of Er₂ O₃ optimizes the electronic structure of Co through Er(4f)-O(2p)-Co(3d) gradient orbital coupling, resulting in significantly enhanced ORR performance. Through gradient orbital coupling, the induced spin-up hole in Co 3d states endows the Er-O-Co unit active site with a spin-selective coupling channel for electron transition. This favors the decrease of the energy gap in the potential-limiting step, thus achieving a high theoretical limiting potential of 0.77 V_RHE for the Er₂ O₃ -Co. Moreover, the potential practicability of Er₂ O₃ -Co/CNF as an air-cathode is also demonstrated in Zn-air batteries. This work is believed to provide, new perspectives for the design of efficient ORR electrocatalysts by engineering spin-selective coupling induced by rare-earth oxides.

Keywords: Er-O-Co unit site; Zn-air batteries; gradient orbital coupling; oxygen reduction reaction; spin regulation.