Unveiling the Stacking Faults in Fe2B Induces a High-Performance Oxygen Evolution Reaction

Fe2B is a potentially promising electrocatalyst for the oxygen evolution reaction (OER) due to its excellent electronic conductivity, which is superior to that of traditional oxide catalysts. However, the activity of Fe2B is still not satisfactory. In this study, meta-stable microstructure stacking faults (SFs) were incorporated into Fe2B through a one-step high-pressure and high-temperature (HPHT) method. Pressure suppressed atomic diffusion but formed SFs when the grain grew. Fe2B with SFs exhibited remarkable OER activity, with low overpotential values of only 269 and 344 mV required to reach current densities of 10 and 100 mA cm(-2), respectively; because of the presence of SFs, the overpotential for the OER was reduced to only 67.7% of that of Fe2B without SFs at 10 mA cm(-2). Theoretical and experimental investigations confirmed that these SFs regulate the d-band center of Fe2B toward the Fermi level, optimizing the catalytic site activity. Furthermore, SFs reduced the charge transfer between Fe atoms and boron (B) atoms, increasing the number of free electrons in the structure and thereby increasing conductivity. Finally, this study suggests a strategy to construct microstructures in crystals, providing new insights into designing excellent catalysts via microstructure engineering.