Regulated iron corrosion towards fabricating large-area self-supporting electrodes for efficient oxygen evolution reaction

Exploring cost-effective electrodes operating at a high current density above 400 mA cm−2 is still challenging for the industrial application of water splitting. Herein, the corrosion layers of iron foam are tailored towards preparing self-supporting electrodes for the oxygen evolution reaction (OER). Corrosion reactants (Ni2+, O2 and H2O) are adopted to regulate the structures and electrochemical performances of electrodes on account of the diverse iron corrosion behaviors. By further comparing the spontaneous iron corrosion in ZnCl2, CoCl2, NiCl2 and FeCl3 solutions, it is identified that the appropriate electrode potentials of Ni/Ni2+ and Co/Co2+ are favourable for achieving uniformly ordered corrosion layers owing to the simultaneously occurring oxygen corrosion and replacement reaction. The as-prepared electrode exhibits excellent OER performances of affording low overpotentials of 221 and 291 mV to reach 100 and 500 mA cm−2, respectively, as well as steadily operating at 500 mA cm−2 for 100 h. Integrating with a prominent hydrogen evolution reaction (HER) catalyst, an industrially required current density of 500 mA cm−2 has been obtained at 1.81 V. Importantly, a large-area electrode (8 × 8 cm2) has been successfully prepared. This work establishes potential possibilities for designing inexpensive and efficient electrocatalysts through regulated metal corrosion.