Deep Eutectic Solvent-Mediated Hierarchically Structured Fe-Based Organic–Inorganic Hybrid Catalyst for Oxygen Evolution Reaction

The genuine active sites toward oxygen evolution reaction (OER) are usually generated via the in situ transformation of initial electrocatalysts during anodic oxidation. In principle, all the catalysts possessing such a transition might be active toward OER. However, current OER electrocatalysts are still mainly limited in metal oxides, (oxy)hydroxides, phosphides, and chalcogenides, etc. Little attention is paid to the rational design of electrocatalysts based on the transformation-induced strategy. Herein, we demonstrated a Fe-based organic–inorganic hybrid strategy for the construction of OER electrocatalysts based on the in situ transformation. Hierarchically three-dimensional (3D) iron alkoxides of glycerol were synthesized in choline chloride (ChCl)/glycerol deep eutectic solvent (DES). During the OER, the as-prepared Fe-based organic–inorganic hybrid can transform into FeOOH, an active species for electrocatalysis, exhibiting sustainable electrocatalytic performance. It only requires 280 mV to offer a current density of 10 mA cm–2 and has a small Tafel slope of 47 mV decade–1 in 1 M KOH solution, outperforming most reported Fe-based catalysts. This work provides the concept of DES-mediated organic–inorganic hybrid materials as transformation-induced catalysts toward OER, thus casting new light on the rational design of advanced electrocatalysts for water splitting.