Accelerating corrosion of iron foam enables a bifunctional catalyst for overall water splitting†

To facilitate the green hydrogen economy, it is essential to establish an economical, secure, and large-scale method for producing highly efficient electrocatalysts capable of facilitating overall water splitting. Herein, we demonstrate a facile approach by growing nickel–iron nanoparticles and layered double hydroxide (LDH) nanosheet composites in situ on a Fe-foam substrate via ammonium chloride-assisted corrosion at room temperature. This method does not require electrical input, high temperature, or a tedious synthesis procedure. The obtained catalyst exhibits high catalytic activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), providing a high current density of 500 mA cm⁻² at an overpotential of 270 mV for the OER and 183 mV for the HER. In addition, the catalyst that serves as both the cathode and anode for overall water splitting also exhibits satisfactory performance with a low cell voltage of 1.55 V at 10 mA cm⁻² with high stability at different current densities from 10 to 300 mA cm⁻² for 70 h. Our findings underline a highly efficient and scalable strategy for the large-scale preparation of bifunctional electrocatalysts for alkaline water electrolysis.