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.