Interface Engineering Construction of a Ag-Modified Crystalline CoFe@Amorphous Fe₂O₃ Composite for Superior Oxygen Evolution Electrocatalysis

Abstract

The sluggish kinetics of the oxygen evolution reaction (OER) is a key resistance limiting the efficiency of related technologies. CoFe-based compounds, mainly alloys and oxides, are recognized as effective OER catalysts, with amorphous metal oxides displaying unique properties. The catalytic activity of a catalyst is intricately linked to its surface reactivity. However, efforts to construct composites with interfaces between CoFe-based metal alloys and amorphous metal oxides to further enhance the OER activities have progressed relatively slowly. In this work, a composite catalyst, denoted Ag/CoFe/Fe 2 O 3 /NC, was fabricated by incorporating Ag into crystalline CoFe@amorphous Fe 2 O 3 particles wrapped in graphitic N-doped carbon. The composite exhibited modulated electron density of Co active sites, promoted O 2 release, and an enhanced electron transfer rate on the heterogeneous interface between crystalline CoFe and amorphous Fe 2 O 3 . Additionally, the introduction of highly conductive Ag improved the electrical conductivity. Consequently, the composite demonstrated excellent performance and stability for OER in 1 M KOH. Notably, the catalyst exhibited competitive performance, requiring overpotentials of only 166 and 282 mV at 10 and 100 mA cm −2 , respectively. This places the catalyst among the most efficient, as far as we know. This work provides an excellent example of the rational design of electrocatalysts.