Selenium-activated monolithic FeNi layered double hydroxide electrodes: binder-free, self-supported architectures for durable alkaline oxygen evolution

Abstract

Developing earth-abundant, durable, and scalable oxygen evolution electrocatalysts is critical for alkaline water electrolysis. Herein, a monolithic, binder-free Se-activated FeNi layered double hydroxide (Se–FeNi-LDH) electrode grown directly on an ultrathin FeNi alloy substrate is introduced. This integrated architecture eliminates polymeric binders and interfacial resistance, enabling efficient electron/mass transport under industrial conditions. The optimized FeNi-LDH1-Se₀₅ electrode delivers outstanding OER activity with overpotentials of only 240 and 290 mV at 10 and 100 mA cm⁻², respectively, a low Tafel slope of 37 mV dec⁻¹, and stable operation for 120 h at 100 mA cm⁻². In a practical electrolyzer (Se–FeNi-LDH‖Pt), a cell voltage of 1.56 V at 10 mA cm⁻² is achieved. Selenium incorporation modulates the electronic structure of Fe/Ni centers, enhances active surface area and charge-transfer kinetics, and maintains high faradaic efficiency (∼97.5%). This work establishes selenium activation in a binder-free monolithic LDH platform as a scalable, mechanically robust strategy for high-performance alkaline OER.