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_NanoporouslCRNi_Nanoporous device delivers a current density of 100 mA/cm² 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.