Surface-Activated Amorphous Iron Borides (FexB) as Efficient Electrocatalysts for Oxygen Evolution Reaction

The development of efficient and earth-abundant water-splitting electrocatalysts is of great importance for energy conversion and storage technologies. In this study, surface-activated amorphous FexB catalysts, Fe-B-O@Fe2B and Fe-B-O@FeB2, are synthesized and remarkable activity for the oxygen evolution reaction (OER) is achieved, e.g., Fe-B-O@FeB2 delivering a current density of 10 mA cm(-2) at overpotential of 260 mV with Tafel slope of 57.9 mV dec(-1) for OER in alkaline electrolyte. Iron oxide/hydroxide and oxidized borate species on the surface of FexB are found to have a synergistic effect on promoting the OER activity of the sample. Moreover, it is found that the OER active oxidization layer of iron boride is less active toward hydrogen evolution reaction.