Scalable Synthesis of Amorphous NiFe Oxide Hollow Microspheres via Glucose-Mediated Spray Pyrolysis for Industrial Hydrogen Production

Abstract

Developing high-performance, low-cost oxygen evolution reaction (OER) catalysts is crucial for advancing anion exchange membrane water electrolysis (AEMWE) in large-scale industrial green hydrogen production. Herein, We report a glucose-mediated spray pyrolysis method for synthesizing amorphous NiFe bimetal oxide hollow microspheres (A-NiFeOx) with controlled crystallinity, hierarchical porosity, and atomic-level compositional uniformity. Glucose acts as a dynamic template, guiding hollow structure formation through a self-limiting gas expansion mechanism and stabilizing the amorphous phase via kinetic trapping. The optimized A-NiFeOx-400 catalyst achieves ultralow overpotentials of 248 mV at 10 mA cm-2, 274 mV at 50 mA cm-2, and 288 mV at 100 mA cm-2, outperforming both its crystalline counterparts and commercial RuO2. Operando spectroscopic analysis confirms that A-NiFeOx-400 primarily follows the adsorbate evolution mechanism (AEM) under high current densities. Density functional theory (DFT) calculations show that structural amorphization induces localized charge redistribution around Fe centers, lowering the OER energy barrier by 0.72 eV through enhanced *OOH adsorption. In practical AEMWE systems, A-NiFeOx-400 achieves an unprecedented industrial current density of 10 A cm-2 at 3.56 V, while maintaining remarkable stability with approximately 1.25 % activity decay over 800 h operation at 1 A cm-2. This method is scalable across 11 transition metal oxides and produces over 10 grams in 4 hours. By integrating atomic-scale electronic engineering with industrial manufacturability, it establishes a model for designing next-generation electrocatalysts for gigawatt-scale hydrogen production.