Phase-controlled Er2O3–Co Mott-Schottky heterostructures for efficient bifunctional oxygen electrocatalysts toward long-lifespan rechargeable zinc–air batteries

Regulating phase composition and constructing integrated heterostructures have proven to be an effective strategy for enhancing bifunctional oxygen electrocatalysis and improving the performance of zinc–air batteries. Herein, a series of Co, Er, and N co–doped carbon–based electrocatalysts with nanocubic framework structures composed of Co, Er 2 O 3 , and Co 3 O 4 phases were derived from zeolitic imidazolate framework-67 (ZIF-67) by tuning the Er content (0%, 1%, 3%, 4%, 5%, 6%, etc.). Experimental and physicochemical characterizations reveal that when the Er doping amount reaches 4% (Er(4)–Co/NC), the catalyst exhibits a higher density of defect structures and a larger pore size compared to other electrocatalysts. Meanwhile, the formation of a Er 2 O 3 –Co Mott–Schottky heterojunction composed of an appropriate ratio of Co and Er 2 O 3 phases significantly optimizes the electronic structure of Er(4)–Co/NC. In situ Raman spectroscopy further demonstrates that after 4% Er incorporation, the Er(4)–Co/NC catalyst shows lower overpotentials for the adsorption of the four OER intermediates (*OH − , *OOH − , *O − , and *O 2 − ). Consequently, Er(4)–Co/NC delivers a half-wave potential of 0.91 V for the oxygen reduction reaction (ORR) and an overpotential of 0.31 V at 10 mA cm −2 for the oxygen evolution reaction (OER), indicating its effective bifunctional ORR/OER performance. The corresponding rechargeable zinc–air battery (ZAB) achieves an ultralong cycling lifetime exceeding 1000 h (3000 cycles) and also displays excellent performance in flexible zinc–air battery configurations. This work is expected to broaden the application scope of rare–earth–element doping and ZIF–derived materials in oxygen electrocatalysis and metal–air battery devices.