Oxygen 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.

Two-dimensional transition metal dichalcogenides (TMDs) have been widely considered as potential hydrogen evolution reaction (HER) catalysts because of their low cost and good electrochemical stability in acid conditions. The mechanism of hydrogen adsorption on TMDs plays an important role in optimizing HER activity. In this research, a series of TMDs (MX₂, M = Co, Cr, Fe, Mn, Mo, Nb, Ni, Re, Sc, Tc, Ti, V, W, Zr, and X = S, Se, Te) in 2H- and 1T-phases were investigated using density functional theory to determine the relationship between hydrogen adsorption free energy (ΔG_H) and electronic structure using a simple descriptor. The results showed a positive linear relation between ΔG_H and the work required of the H electron to fill the unoccupied electronic states of the TMDs. Based on such linear relationships, the various defects (B-, C-, N-, O-, F-, P-, Se-doping and S-vacancy) were used to activate the inert basal planes of the 2H-phase molybdenum disulfide, which can introduce impurity states in the lower energy level to effectively accommodate the H electron. Furthermore, HER activity can be further optimized with the increasing concentration of the defects. These findings provide a practicable map of the HER performances, as well as indicating an appropriate direction for optimizing HER activity.

A CeO₂/Fe–Co(OH)₂ heterostructure catalyst featuring flexible redox states of Ce^δ+ as an electronic buffer, enabling dynamic regulation of Co(ii/iii/iv) and enhancing both activity and stability.