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 Fe x B catalysts, Fe–B–O@Fe 2 B and Fe–B–O@FeB 2 , are synthesized and remarkable activity for the oxygen evolution reaction (OER) is achieved, e.g., Fe–B–O@FeB 2 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 Fe x B 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.