FeOOH stabilizes and modulates Cu(OH)2 for efficient ampere-level electrolysis of water at elevated temperatures

Fe- and Cu-based catalysts are top candidates for the oxygen/hydrogen-evolution reactions, but their large-scale application is limited by rapid degradation under prolonged operation, especially at high current densities and high temperatures. Herein, a FeOOH/Cu(OH) 2 nanotube array grown on copper foil was designed for overall water-splitting. The structure enhances the electrochemical surface area, increases catalytic site density, and accelerates gas transport. DFT calculations confirms the Cu(OH) 2 and FeOOH synergy weakens HO–H bond, optimizing the ∗H adsorption energy, and driving reaction kinetics. In 1 M KOH, it achieves HER overpotentials of only 89 and 244 mV, and OER overpotentials of 124 and 424 mV at 10 and 100 mA cm −2 , respectively. Under industrial conditions (30% KOH, 65 °C), it sustains >2 A cm −2 for 100 h with negligible HER activity loss. This work provides a practical guide for designing high-activity, ultra-stable ampere-level water-splitting catalysts.