Engineering Ultrafine NiFe‐LDH into Self‐Supporting Nanosheets: Separation‐and‐Reunion Strategy to Expose Additional Edge Sites for Oxygen Evolution

Abstract Here, a strategy is reported to prepare Ni‐Fe layered double hydroxide (NiFe‐LDH) with abundant exposed edge planes for enhanced oxygen evolution reaction (OER). The edge‐to‐edge assembly of ultrafine NiFe‐LDH directed by graphite‐like carbon is performed through a one‐step hydrothermal process to form self‐supporting nanosheet arrays (named NiFe‐LDH/C), in which ascorbic acid is employed as the carbon precursor to control both the platelet size and the assembly mode of NiFe‐LDH. Benefiting from the unique structural engineering, NiFe‐LDH/C can not only achieve a fast surface reconstruction into the highly active γ‐phase structure, but also exposes abundant active edge sites, thus leading to a superior OER performance with the overpotential as low as 234 mV at a current density of 50 mA cm −2 . Furthermore, density functional theory (DFT) calculations reveal that the unsaturated Fe‐sites and the bridge‐sites connecting Ni and Fe atoms, which only exist on the edge planes of NiFe‐LDH, are the main active centers responsible for promoting the intrinsic OER activity. This work provides a specific and valuable reference for the rational design of high‐quality electrocatalysts through structural engineering for renewable energy applications.