Electrochemically Reconstructed Cu‐FeOOH/Fe₃O₄ Catalyst for Efficient Hydrogen Evolution in Alkaline Media

Abstract Surface self‐reconstruction via incorporating an amorphous structure on the surface of a catalyst can induce abundant defects and unsaturated sites for enhanced hydrogen evolution reaction (HER) activity. Herein, an electrochemical activation method is proposed to reconstruct the surface of a Cu‐Fe₃O₄ catalyst. Following a “dissolution–redeposition” path, the defective FeOOH is formed under potential stimulation on the surface of the Cu‐Fe₃O₄ precursor during the electrochemical activation process. This Cu‐FeOOH/Fe₃O₄ catalyst exhibits excellent stability as well as extremely low overpotential toward the alkaline HER (e.g., 129 and 285 mV at the large current densities of −100 and 500 mA cm⁻², respectively), much superior to the Pt/C catalyst. The experimental and density functional theory calculation results demonstrate that the Cu‐FeOOH/Fe₃O₄ catalyst has abundant oxygen vacancies, featuring optimized surface chemical composition and electronic structure for improving the active sites and intrinsic activity. Introducing defective FeOOH on the surface of a Cu‐Fe₃O₄ catalyst by means of an electrochemical activation method decreases the energy barrier of both H₂O dissociation and H₂ generation. Such a surface self‐reconstruction strategy provides a new avenue toward the production of efficient non‐noble metal catalysts for the HER.