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

Abstract 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.