Electronic modulation at Co-O-Fe bridges in a dual-MOF heterostructure for efficient oxygen evolution

Co-O-Fe electronic modulation lowers OER overpotential to 169 mV at 10 mA cm −2 . • Rapid interfacial charge transfer yields a low Tafel slope of 106.4 mV dec − ¹ mV dec −1 . • Fe-to-Co electron transfer optimizes the D-band center for OER intermediates. • Heterointerface prevents MOF aggregation and exposes abundant active sites. Overcoming the sluggish kinetics of the oxygen evolution reaction (OER) remains a primary bottleneck in advancing sustainable hydrogen generation technologies. Herein, a dual-metal-organic-framework (dual-MOF) heterostructure, ZnCo-ZIF@MIL-100 (denoted as ZM-3), was constructed via a one-step hydrothermal method, where MIL-100 frameworks were epitaxially grown on orthododecahedral ZnCo-ZIF templates. This core-shell heterostructure inherits the structural merits of both MOF phases, achieving 10 mA cm − ² at an overpotential of 169 mV with a Tafel slope of 106.4 mV dec − ¹ in 1.0 M KOH. Comprehensive characterisation (XRD, SEM/TEM, XPS, etc.) and electrochemical analysis verify that heterostructure formation triggers notable electron redistribution from Fe to Co centres, optimises interfacial charge transfer and boosts accessible catalytic sites. DFT calculations further confirm that interfacial Co-O-Fe bridge sites tune the adsorption energetics of oxygenated intermediates, reducing the energy barrier of the potential-determining step. This work offers an interfacial regulation strategy for developing advanced MOF-based oxygen evolution electrocatalysts. ZM-3 exhibits a low overpotential, a small Tafel slope (106.4 mV dec −1 ) and long-term stability for OER. Download: Download high-res image (202KB) Download: Download full-size image