A high-entropy FeCoMnCuNi diselenide self-standing electrode with outstanding water-electrolysis performance in alkaline medium†

Developing non-noble metal efficient electrocatalysts with high activity and stability is extremely essential for hydrogen generation by water electrolysis with low cost. Herein, we report a novel binder-free high-entropy self-standing electrode with a unique three-dimensional structure and petunia-, needle- and fork-like morphology prepared by the hydrothermal and selenization methods. Due to high entropy, lattice distortion and high-curvature tip-enhancement effects, the prepared FeCoMnCuNiSe₂ with an ultralow overpotential of 71.6 mV at 100 mA cm⁻² exhibited superior activity for the hydrogen evolution reaction (HER) in 1.0 M KOH solution, far outperforming almost all reported advanced non-noble metal HER catalysts. More impressively, the assembled FeCoMnCuNiSe₂||FeCoMnCuNiSe₂ overall-water splitting device with more than 45 h of continuous operational stability at 10, 20 and 50 mA cm⁻² in 1.0 M KOH required a remarkably low cell voltage of 1.30 V at 10 mA cm⁻² as well, demonstrating a promising practical application prospect in future water electrolysis.