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

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/Fe2O3/NC, was fabricated by incorporating Ag into crystalline CoFe@amorphous Fe2O3 particles wrapped in graphitic N-doped carbon. The composite exhibited modulated electron density of Co active sites, promoted O2 release, and an enhanced electron transfer rate on the heterogeneous interface between crystalline CoFe and amorphous Fe2O3. 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.