Dynamic Electron Spring Effect in Hollow Fe2O3/CoSe2 Heterostructure Enhance Ethanol Electro-Oxidation Activity and Stability

Abstract

Developing efficient non-noble electrocatalysts with high activity and selectivity for ethanol oxidation reaction (EOR) across a wide potential range remains a significant challenge in hybrid energy systems. Herein, hollow Fe₂O₃/CoSe₂ heterostructures (H-Fe₂O₃/CoSe₂@C) via interface engineering are reported as highly effective EOR promising electrocatalysts. Characterizations reveal that Fe₂O₃ functions as a dynamic electron spring to tune the electronic structure of Co sites, accelerating the formation of the Fe₂O₃/CoOOH heterostructure while suppressing Fe₂O₃/CoO₂ evolution. In situ Raman spectroscopy and theoretical calculation confirm that the Fe₂O_3/CoOOH heterostructure enhances EOR kinetics and lowers the energy barrier of the potential-determining step. Quasi in situ X-ray photoelectron spectroscopy further demonstrates that Fe₂O₃ stabilizes Co³⁺against overoxidation, expanding the operational potential window. Consequently, H-Fe₂O₃/CoSe₂@C achieves outstanding EOR performance, exhibiting 10 mA cm⁻² @1.30 V vs. RHE with a high faradaic efficiency of 99% at 1.30 V. Ethanol-assisted Zn-Air battery/water splitting devices based on H-Fe₂O₃/CoSe₂@C demonstrate enhanced energy conversion efficiency, with voltage reduced by 210 and 180 mV at 10 mA cm⁻², respectively. This work provides critical insights for designing heterostructure electrocatalysts and advancing the utilization of biomass energy.