In Situ Grown Bimetallic (Ni, Fe)₁₂P₅ Nanoneedles With Favorable Electronic Structures and Superwetting Surfaces for Highly Efficient and Durable Seawater Splitting at Industrial Current Density

Abstract

Developing a highly efficient, stable, and industrially adaptable bifunctional electrode is crucial for green hydrogen production from seawater electrolysis. Herein, 3D nanoneedle-like Fe-doped Ni₁₂P₅ arrays anchored on nickel foam (Fe–Ni₁₂P₅ NAs@NFF) are in situ fabricated by a facile one-step phosphorization route. Profiting from the favorable electronic configuration and self-supporting structure with superwetting surfaces, this material demonstrates exceptional performance in alkaline seawater, requiring low overpotentials of 369 and 367 mV to achieve 1000 mA cm⁻² for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) and ensuring stable long-term durability of over 2000 h. When applying Fe–Ni₁₂P₅ NAs@NFF as both anode and cathode in an anion exchange membrane electrolyzer, it delivers a cell voltage of only 1.87 V at 1000 mA cm⁻² and maintains stable operation for over 140 h, outperforming commercial benchmarks. Based on the collective in situ experimental analysis and theoretical calculation, it is demonstrated that the Ni–Fe–P coordination in bimetallic phosphides delivers the favorable electronic structure, facilitates the reconstruction of OER-active species, and ameliorates the hydrogen adsorption energy for HER. Additionally, the superwetting ability in the surface enables efficient gas bubble detachment and active center regeneration, while the free-standing structure prevents catalytically active components from peeling off, endowing robust stability at the industrial-level current. This work provides new insights into designing and synthesizing highly efficient and stable bifunctional catalysts for seawater electrolysis and contributes to the strategy for large-scale production of low-cost renewable hydrogen at industrial current density.

Keywords

bimetallic phosphides / favorable electronic configuration / industrial-scale current density / seawater electrolysis / superwetting surfaces

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