Coral‐Reef‐Like Nanoporous Nickel Architecture for Enhanced Oxygen/Hydrogen Evolution Reaction and Alkaline Water Electrolysis

ABSTRACT 3D porous nickel (Ni) materials are promising electrocatalysts for alkaline water electrolysis; however, their practical application is hindered by the sluggish hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this work, a coral‐reef‐like nanoporous Ni architecture (denoted as CRNi Nanoporous ) is directly fabricated on a free‐standing Ni foam (Ni Foam ) via potentiostatic deposition of a Ni‐copper (NiCu) alloy followed by electrochemical dealloying. Structural characterization reveals that the CRNi Nanoporous consists of interconnected 2D nanosheets with a mixed crystalline‐amorphous heterostructure and superhydrophilic surface. Benefiting from abundant active sites, enhanced charge transfer kinetics, and a large electrochemical surface area, the self‐supported CRNi Nanoporous electrode exhibits markedly improved OER and HER activities compared with commercial Ni Foam and Ni felt (Ni Felt ) in 1 m KOH solution. When employed as both the anode and cathode in a lab‐scale flow electrolyzer with an anion exchange membrane, the CRNi Nanoporous lCRNi Nanoporous device delivers a current density of 100 mA/cm 2 at a cell voltage of 1.8 V. This work demonstrates the significant potential of low‐cost, structurally engineered Ni‐based catalyst for efficient alkaline water electrolysis.