Interface engineering-induced built-in electric field in Fe2O3/CeO2 heterojunction for superior oxygen reduction electrocatalysis

Developing cost-effective and durable oxygen reduction reaction (ORR) electrocatalysts is pivotal for the commercialization of zinc-air batteries (ZABs). Herein, nitrogen-doped porous carbon-supported Fe 2 O 3 /CeO 2 heterojunction electrocatalysts (Fe 2 O 3 /CeO 2 @NC) were synthesized via a supramolecular confinement strategy. By leveraging the melamine-folic acid framework to anchor FeCe Prussian blue analogues, a hierarchical porous carbon structure with uniform heterojunction nanoparticle dispersion was successfully constructed. Experimental characterization and DFT calculations reveal that the distinct work function difference between Fe 2 O 3 and CeO 2 induces spontaneous electron transfer, establishing a built-in electric field at the heterointerface. Synergized with abundant oxygen vacancies, this electronic modulation effectively optimizes the adsorption free energy of oxygen intermediates and lowers the rate-determining energy barrier. Consequently, the Fe 2 O 3 /CeO 2 @NC catalyst exhibits superior ORR activity with a half-wave potential of 0.83 V, rivaling commercial Pt/C, along with excellent methanol tolerance. Furthermore, the assembled liquid ZABs deliver a high peak power density of 146.4 mW cm −2 and demonstrate robust rechargeability for over 200 h, highlighting its potential for practical energy conversion applications.