Asymmetric Fe−O(P)−Ni Coordination Coupled with Oxygen Vacancies Boosting Deep Reconstruction of Fe-NPO for Industrial AEM Water Electrolysis

Abstract

Targeted regulation of electrocatalyst reconstruction during the oxygen evolution reaction (OER) under alkaline conditions proves essential to achieving highly efficient hydrogen production via electrochemical water splitting. Yet this remains a considerable challenge. Herein, we prepare an iron nickel phosphate (Fe-NPO) catalyst, which possesses substantial oxygen vacancies and an asymmetric Fe-O(P)-Ni coordination structure. This structural merit facilitates the effective deep reconstruction of Fe-NPO, which then transforms into the highly active Fe-Vo-P-NiOOH active phase during OER. For the reconstructed Fe-Vo-P-NiOOH, it effectively tunes the d-band center, bringing it notably closer to the Fermi level. This type of electronic modulation not only strengthens the water adsorption capacity but also optimizes the rate-determining step (RDS) in the OER pathway. The anion-exchange membrane water electrolyzer (AEMWE) integrated with the Fe-NPO catalyst as an anode catalyst achieved high industrial current densities of 500, 1000, 1500 and 2000 mA cm-2 at low applied voltages of 1.68, 1.76, 1.84 and 1.92 V, respectively. This work presents a strategy to realize the deep and efficient conversion of OER catalysts into highly active components through defect engineering and asymmetric coordination regulation, while also confirming Fe-NPO’s considerable potential for practical hydrogen production scenarios.