One stone two birds: Fe3+ ions as corrosion agent and catalyst for one-step synthesis of nickel‑iron layered double hydroxide @polypyrrole composite for water splitting

Layered double hydroxides (LDHs) have garnered broader attention as electrocatalytic materials due to their low cost, structural tunability, and high specific surface area. However, the intrinsic low activity and poor electrical conductivity of LDHs pose challenges that hinder their further application in the field of electrocatalysis. Herein, we synthesized nickel‑iron layered double hydroxide @polypyrrole (NiFe-LDH@PPy) composite electrocatalyst through a one-step method with Fe 3+ ions eroding Ni foam to form NiFe-LDH and simultaneously as catalyst to synthesis PPy at room temperature. The NiFe-LDH@PPy composite achieves low overpotentials of 236 mV for the oxygen evolution reaction (OER) and 95 mV for the hydrogen evolution reaction (HER) at a current density of 10 mA cm −2 . Notably, the constructed water electrolysis cell with NiFe-LDH@PPy as cathode and anode only requires a water electrolysis voltage of 1.57 V at 10 mA cm −2 . The excellent water-splitting performance is attributed to the high electronegativity of nitrogen in PPy and its superior conductivity.