Surface Reconstruction-Promoted Alkaline Overall Water Splitting on Fe-Doped Ni₂P/NiMoO₄ Composite Structure

Abstract

Nickel-based catalysts hold significant promise for efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) due to their dynamic reconstruction capability. However, uncontrolled reconstruction promotes lattice oxygen participation, triggering the destructive lattice oxygen-mediated mechanism (LOM) that causes rapid catalyst disintegration at industrial current densities. Herein, we resolve the challenge through Fe doping-enabled selective adsorbate evolution mechanism (AEM) pathway engineering in a Ni₂P/NiMoO₄ heterostructure (Fe-Ni₂P/NiMoO₄). During OER, Fe doping triggers deep reconstruction into Ni(Fe)OOH while suppressing the LOM via electronic modulation, yielding an AEM with optimized OH* adsorption. This mechanism-selective design delivers exceptional bifunctional performance: 140 mV (HER) and 256 mV (OER) overpotentials at 100 mA cm⁻², sustained stability at 200 mA cm⁻² for 100 h (HER and OER) and 50 mA cm⁻² for 100 h (overall water splitting). Mechanistic studies reveal Fe doping's dual role: (i) accelerating reconstruction kinetics to form Ni(Fe)OOH as the AEM-active phase and (ii) stabilizing the Fe-Ni₂P conductive backbone by eliminating oxygen-loss pathways. This work pioneers mechanism-selective reconstruction as a design principle for industrial electrocatalysts, moving beyond empirical activity optimization toward rational pathway control.

Keywords

bifunctional catalyst / element doped / nickel molybdate / surface reconstruction

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2026 The Author(s). Electron published by Harbin Institute of Technology and John Wiley & Sons Australia, Ltd.