Deep Eutectic Solvent‐Mediated Construction of Oxygen Vacancy‐Rich Fe‐Based Electrocatalysts for Efficient Oxygen Evolution Reaction

Abstract Fe‐based catalysts are promising candidates for water splitting due to the abundant reserves of Fe. However, their electrocatalytic performance toward the oxygen evolution reaction (OER) is still unsatisfactory. Herein, a new hybrid catalyst of Fe₇S₈/Fe₂O₃ is designed via a deep eutectic solvent (DES)‐based strategy. The Fe₇S₈/Fe₂O₃ particles are in a porous nanosheet structure and possess oxygen vacancy‐rich characteristics. The porous nanosheet structure and oxygen vacancy‐rich Fe₂O₃ in the Fe₇S₈/Fe₂O₃ significantly improves the electrocatalytic activity toward the OER. The as‐prepared Fe₇S₈/Fe₂O₃ nanosheets demonstrate a small overpotential of 229 mV at a current density of 10 mA cm⁻² with a small Tafel slope of 49 mV dec⁻¹, which outperform most of the state‐of‐the‐art Fe‐based catalysts. This work not only reports a new Fe‐based electrocatalyst with an improved performance toward the OER but also provides a rational DES‐based strategy for construction of advanced catalysts.