Cascading reconstruction to induce highly disordered Fe-Ni(O)OH toward enhanced oxygen evolution reaction

Rational design of pre-catalysts is a powerful yet challenging strategy to realize high-efficient oxygen evolution reaction (OER) through electrochemical reconstruction. Herein, a well-designed pre-catalyst composed of nickel hexacyanoferrate (NiHCF) nanocubes on crystalline Ni(OH)₂ nanosheets is demonstrated to achieve outstanding OER catalysts via cascading reconstruction. The NiHCF phase experiences a complete reconstruction and simultaneously functions as an inducing mediator to enable the reconstruction of the underneath Ni(OH)₂ to form highly disordered Fe-Ni(O)OH. Benefiting from the cascading reconstruction process, the electrode shows obvious self-activation behavior with a notable overpotential decrease of 92 mV at 10 mA cm⁻² relative to that of the pristine catalysts. Accordingly, the as-activated highly disordered Fe-Ni(O)OH exhibits excellent OER performance with an ultralow overpotential of 242 mV to drive the current density of 10 mA cm⁻² and good stability at about 100 mA cm⁻² over 100 h. The facile cascading reconstruction strategy offers a new perspective for obtaining superior catalysts toward OER.