Growth of superhydrophilic metal-oxyhydroxide layer as “firebreak forest” for exponentially enhanced stability in seawater splitting

Developing an active and stable nonprecious-metal-based oxygen evolution catalyst is crucial for boosting green hydrogen industry via direct seawater splitting. However, it has been a significant challenge due to electrode deactivation caused by chloride corrosion. Herein, a nickel-cobalt oxyhydroxide layer is grown on Ni foam via a reconstruction-complete coating strategy. The dense and superhydrophilic oxyhydroxide layer could facilitate the adsorption of abundant OH− ions, which could repel the Cl− ions via electrostatic repulsive force. Consequently, the electrode shows exponentially enhanced stability and superior activity for oxygen evolution reaction (OER) in the electrolyte of 1.0 M KOH + 2.0 M NaCl. It requires a low overpotential of 330 mV to achieve a current density of 100 mA cm−2 and operates stably over 70 h at a large current density of 500 mA cm−2. This work presents a facile strategy for preparing high-performance seawater-splitting catalyst.