Cobalt based anode for highly stable alkaline water electrolysis under operation conditions beyond industrial requirements

Alkaline water electrolysis is the most established route to electrochemical hydrogen production, but the limited lifetime of anode catalysts makes long-term equipment investment costly and hinders miniaturization. Here we show that, unlike the extensively investigated nickel- and nickel–iron-based hydroxides, the long-neglected cobalt–nickel hydroxides are promising anode catalysts whose stability exceeds current industrial requirements. A cobalt–nickel layered double hydroxide anode enables stable alkaline water electrolysis for more than 8,000 hours at 1 A cm–2 in 6 M sodium hydroxide at 80 °C. This stability arises from the strengthened metal–oxygen bonding of the in-situ-formed cobalt–nickel oxyhydroxide, which raises the energy barrier for lattice-oxygen loss during the oxygen evolution reaction. In a practical electrolyzer, the anode achieves an energy consumption of ~4.2 kWh per normal cubic metre of hydrogen at 1 A cm–2 and operates stably for thousands of hours. The design of high-current-density alkaline electrolyzers should therefore prioritize robust anode stability under industrial conditions in addition to activity optimization. Hydrogen production by alkaline water electrolysis is limited by anode durability under industrial conditions. Here, the authors demonstrate a cobalt–nickel layered double hydroxide anode that sustains operation for over 8,000 h at 1 A cm⁻² in 6 M NaOH at 80 °C, enabling durable hydrogen production.