Cathodic corrosion activated Fe-based nanoglass as a highly active and stable oxygen evolution catalyst for water splitting

Abstract

Transition metal-based amorphous alloys have attracted increasing attention as precious-metal-free electrocatalysts for oxygen evolution reaction (OER) of water splitting due to their high macro-conductivity and abundant surface active sites. However, the catalysis of bulk amorphous alloy only originates from a few atomic layers of the surface, and the catalytic activity usually rapidly decreases due to the coverage of corrosion products during the OER process. Here, we report a Fe₇₈Si₉B₁₃ nanoglass covered by in situ formed FeOOH (FeOOH@NG) that can perfectly combine self-activation and synergistic catalysis between volume and surface, leading to high activity, fast reaction kinetics, and stability of activity for OER. The Fe₇₈Si₉B₁₃ nanoglass with abundant ordered boundaries introduced in the amorphous matrix is prepared via melt-spinning followed by high-pressure torsion (HPT). Afterwards, a FeOOH layer is introduced on the surface of the nanoglass by a cathodic corrosion activation method. The FeOOH layer not only exposes more active sites, but also generates hydroxyl radicals (OH) in oxygen vacancies to activate the Fe-based nanoglass matrix. The FeOOH@NG generates an overpotential of only 240 mV at 10 mA cm⁻¹ in 1 M KOH, and the Tafel slope is as low as 42 mV dec⁻¹.