Regulation of Morphology and Electronic Structure of FeCoNi Layered Double Hydroxides for Highly Active and Stable Water Oxidization Catalysts

Abstract

Highly efficient electrocatalysts for the oxygen evolution reaction (OER) are very important for various energy storage and conversion systems such as water splitting devices and metal‐air batteries. However, developing OER electrocatalysts with high activity and excellent stability at a high current density remains a considerable challenge. Herein, a facile room‐temperature‐stirring strategy is described to obtain FeCoNi layered double hydroxide nanocages (FeCoNi‐LDHs) using a metal–organic framework as a precursor. The FeCoNi‐LDHs have hollow features, while their walls are assembled with ultrathin layered hydroxide nanosheets. By designing a unique structure and tuning the composition, high activity and robust long‐term stability of the FeCoNi‐LDHs for the OER outperform IrO ₂, used as the reference catalyst. The as‐obtained high electrochemically active surface area and the decreased transfer resistance are ascribed to the significantly improved activity. Density functional theory calculations suggest that the introduction of Fe can fine‐tune the electronic structure and decrease the Gibbs free energy difference of the rate‐determining step (ΔG ₃), improving the intrinsic activity of FeCoNi‐LDHs toward the OER. Furthermore, the proposed room‐temperature‐stirring strategy can be easily scaled up to more than 10 grams of nanocages through a single batch reaction process, demonstrating the large‐scale applicability of the catalysts.