Constructing Co–O–Ce bridge in Mott-Schottky Co/CeO2 heterojunctions facilitates oxygen electrocatalysis bifunctionality for rechargeable Zn-air batteries

Abstract

Designing a heterogeneous interface to improve the kinetics of electrocatalysts represents an effective yet challenging approach for enhancing the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, a simple MOF-assisted etching-pyrolysis strategy is proposed to fabricate an advanced Mott-Schottky (M–S) electrocatalyst composed of Co/CeO₂ hetero-nanoparticles embedded within N-doped hollow carbon nanoboxes (H-Co/CeO₂@NCBs). Notably, the interfacial Co–O–Ce bond bridging productively facilitates the electron transfer and modulates the charge distribution of the active center, thereby contributing to the ORR/OER kinetics. As expected, the optimal M–S H-Co/CeO₂@NCBs catalyst exhibits promising bifunctional electrocatalytic activity with a small potential discrepancy of 0.65 V. Theoretical calculations reveal that the built-in electric field in the M–S heterojunction promotes electron transfer in oxygen electrocatalysis and the interfacial bridge-induced electron redistribution optimizes the adsorption/desorption of the oxygen intermediates, leading to reduced activation energy for the bifunctional ORR/OER reactions. Importantly, H-Co/CeO₂@NCBs-assembled Zn-air battery (ZAB) delivers high power density (179.8 mW cm⁻²) and long-term stability (400 h). Furthermore, the assembled flexible solid-state ZAB with H-Co/CeO₂@NCBs cathode also exhibits excellent charge–discharge reversibility and flexibility at various bending angles. This work provides a novel perspective on developing efficient and stable M–S bifunctional oxygen electrocatalysts.