Hierarchical NiFeMoO Precatalyst Reconstructed NiFeOOH Anodes for Efficient and Durable Anion-Exchange Membrane Water Electrolysis.

Anion-exchange membrane water electrolysis (AEM-WE) offers a promising alternative for efficient water electrolysis, providing low-cost and high-purity hydrogen production. However, the slow reaction kinetics associated with the oxygen evolution reaction (OER) continue to pose a significant obstacle. In this work, we synthesized nanometer micron hierarchical NiFeMoO as OER precatalysts, which were completely reconstructed into hierarchical NiFeOOH (NiFeOOH), demonstrating remarkable OER activity, with overpotentials of 162/245 mV required to achieve current densities of 10/1000 mA cm in 1.0 M KOH. Additionally, it demonstrated robust stability exceeding 1000 h at 1000 mA cm. Furthermore, NiFeOOH demonstrated excellent long-term stability in AEM-WE, maintaining a current density of 1000 mA cm at a cell voltage of 1.55 V (80 °C) for over 160 h and achieving a reliable performance beyond 1000 h at room temperature. analyses, including X-ray absorption fine structure (XAFS), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), combined with density functional theory (DFT) calculations, reveal that the OER process of NiFeOOH primarily follows an adsorption evolution mechanism (AEM) at the Ni site. Meanwhile, Fe acts as a Lewis acid, promoting Ni valence and thereby enhancing the OER performance. This study emphasized the crucial role of precatalyst engineering for efficient NiFe-based catalysts and analyzed the role of Fe in the OER catalytic cycle.