Synthesis of a Nanoporous Oxygen-Vacancy-Rich Iron-Nickel Double Hydroxide Composite as a High-Performance Electrocatalyst for Oxygen Evolution Reaction

In this work, we demonstrate a straightforward method for the synthesis of the high-performance double-hydroxide (Fe(OH) 3 ∥Ni(OH) 2 ) nanoporous composite electrocatalyst for oxygen evolution reaction (OER). A nanoporous Ni(OH) 2 film was electrochemically deposited using water electrolysis, in which hydrogen bubbles acted as a dynamic template, and the generated hydroxide ions caused precipitation of Ni 2+ ions from the solution. The capillary action of nanopores was used to introduce Fe 3+ ions that were precipitated in the nanopores by dipping into a KOH solution. A series of characterization methods and electrochemical techniques were used to characterize the physicochemical properties and electrocatalytic behavior of the prepared catalyst toward OER. Experimental results suggest that the incorporation of Fe(OH) 3 into the nanoporous Ni(OH) 2 film to a level of ∼4%mol can significantly enhance its electrocatalytic activity toward OER. The OER current density observed for as-synthesized Fe(OH) 3 ∥Ni(OH) 2 was higher by a factor of 3.9 compared to the original nanoporous Ni(OH) 2 . The enhanced performance resulted from the interfacial synergistic effects between the two hydroxides, likely due to the improved electronic structure and increased density of oxygen vacancies. Our synthetic method is quite simple, cost-effective, and holds great potential for practical application in water electrolysis.