Ultrafine CoNiFeZrPt high entropy crystals-confined 3D conductive binary alloy nanonetworks promote overall water electrolysis

Crystalline high entropy alloy (HEA) provides a remarkable alternative to create high-efficiency electrocatalysts that go beyond conventional alloys. Herein, we propose a novel hybrid material of dense ultra-small CoNiFeZrPt HEA nanoparticles uniformly immobilized on conductive binary Co–Ni nanowires (CN@CNFZP). The CN@CNFZP hybrid in 1.0 M KOH exhibits a mere (18 and 253) mV of overpotential at 10 mA·cm⁻² for hydrogen and oxygen evolution reactions (HER and OER), respectively, surpassing those of pure CNFZP and recently reported HEA-based catalysts. A single cell of the fabricated anion exchange membrane water electrolyzer stack could effectively deliver a high current response of (0.5 or 1.0) A·cm⁻² at a required stack voltage of (1.75 or 2) V, respectively, along with excellent durability of 900 h at 0.5 A·cm⁻². This study presents a particular catalyst design to actively promote both HER and OER to reach the efficiency of large-scale H₂ production during water splitting.