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

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.