Coupling Adsorbed Evolution and Lattice Oxygen Mechanism in Fe‐Co(OH)2/Fe2O3 Heterostructure for Enhanced Electrochemical Water Oxidation

Abstract

AbstractOxygen evolution reaction (OER) remains a bottleneck for electrocatalytic water‐splitting to generate hydrogen. However, the traditional adsorbed evolution mechanism (AEM) possesses sluggish reaction kinetics due to the scaling relationship, while lattice oxygen mechanism (LOM) triggers an unstable structure due to the escaping of lattice oxygen. Herein, a proof‐of‐concept Fe‐Co(OH)2/Fe2O3 heterostructure is put forward, where Fe‐Co(OH)2 following AEM can complete rapidly deprotonation process while Fe2O3 following LOM can trigger O─O coupling step. Combining the theoretical and experimental investigation confirmed that the redistributed space‐charge of Fe‐Co(OH)2/Fe2O3 junction can optimize synergistically adsorbed and lattice oxygen, the coupling mechanism of AEM and LOM can facilitate synchronously the OER activity and stability. As a result, the Fe‐Co(OH)2/Fe2O3 heterostructure shows excellent OER performance with low overpotential of only 219 and 249 mV to reach a current density of 10 and 100 mA cm−2. Specifically, the Fe‐Co(OH)2/Fe2O3 electrocatalyst maintains excellent long‐term stability for 100 h at a large current density of 100 mA cm−2. This work paves an avenue to break through the limit of the conventional OER mechanism.