An Amorphous Nickel-Iron-Based Electrocatalyst with Unusual Local Structures for Ultrafast Oxygen Evolution Reaction

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient and stable catalysts for the oxygen evolution reaction (OER) is crucial for water splitting technologies.
• Perovskite oxides (ABO₃) are promising OER catalysts due to their tunable properties.
• Leaching of A-site cations in perovskites can generate nanostructures and amorphous phases, enhancing OER activity, but selective control remains challenging.

Purpose of the Study:

• To develop a strategy for selectively dissolving A-site cations and creating active amorphous motifs from B-site cations in perovskite oxides.
• To investigate the potential of a top-down approach for synthesizing novel perovskite-derived OER catalysts.

Main Methods:

• A top-down strategy involving FeCl₃ post-treatment of bulk crystalline lanthanum nickelate (LaNiO₃) perovskite.
• Transformation of the crystalline perovskite into a nanostructured amorphous hydroxide.
• Characterization of the catalyst's structure, surface area, and active sites (dual NiFe).

Main Results:

• The developed amorphous catalyst exhibited an exceptionally low overpotential of 189 mV at 10 mA cm^-2 for the OER.
• The catalyst features a large surface area and dual NiFe active sites, including high-valence Ni³⁺ and distorted Fe octahedra.
• The strategy successfully created nanostructured amorphous motifs from the B-site cations.

Conclusions:

• The top-down strategy effectively transforms crystalline perovskite into a highly active amorphous hydroxide catalyst for the oxygen evolution reaction.
• The resulting catalyst demonstrates superior OER performance due to its unique nanostructure and dual active sites.
• This approach offers a viable pathway for designing advanced perovskite-derived electrocatalysts.