Self‐Supporting Multiscale Porous CoZnNi Bifunctional Electrocatalyst for Highly Efficient Alkaline Water Splitting

ABSTRACT The development of efficient and low‐cost electrocatalysts is crucial for advancing alkaline water electrolysis toward sustainable hydrogen production. Herein, a self‐supported multiscale porous CoZnNi alloy on CoNi foam was easily fabricated via the scalable dealloying protocol based on electrodeposition, annealing, and selective corrosion. The as‐prepared CoZnNi electrode features a continuous three‐dimensional (3D) porous and cracked structure with pore sizes ranging from 3 nm to 1 μm. Benefiting from unblocked electron transport, full electrolyte infiltration, and gas release, the CoZnNi electrode exhibits a markedly reduced overpotential and superior cycling stability. In situ Raman spectroscopy reveals that in CoZnNi, Co and Ni synergistically promote alkaline hydrogen evolution reaction (HER), whereas Co sites catalyze oxygen evolution reaction (OER) through direct O–O coupling. The CoZnNi requires overpotentials of only 302 mV for the HER and 461 mV for the OER to achieve 1000 mA cm −2 , and maintains stability for over 500 h for HER and 300 h for OER. When configured in a two‐electrode system, the CoZnNi(−)||CoZnNi(+) couple delivers 100 mA cm −2 at a low cell voltage of 1.85 V and operates stably for over 300 h. This work offers a practical strategy for designing efficient non‐noble metal electrocatalysts for water splitting.