Lattice Distortion in High‐Entropy Transition Metal Diselenide for Augmented Hydrogen Evolution

The high-entropy strategy offers a viable pathway to activate the inert basal plane of transition metal dichalcogenides (TMDs) for electrocatalysis. This work demonstrates that the "lattice distortion effect", one of the core effects of high-entropy materials, plays a crucial role in activating the basal plane of TMDs. A high-entropy diselenide (ReNbTaMoW)Se₂ (denoted as HESe₂) is synthesized via solid-state reaction. Single-crystal X-ray diffraction and atomic resolution scanning transmission electron microscopy reveal a unique fivefold-modulated structure in HESe₂, which unexpectedly distorts the rigid trigonal prismatic motif. HESe₂ exhibits exceptional activity for hydrogen evolution reaction (HER), showing a low overpotential of 31 mV at a current density of 10 mA cm^-2, comparable to state-of-the-art precious metal catalysts. In situ X-ray photoelectron spectroscopy indicates that the distorted structure of HESe₂ remains stable during the HER process. A proton exchange membrane (PEM) electrolyser assembled with HESe₂ cathodic catalyst shows competitive performance and durability with negligible degradation over 400 h. Density functional theory calculations reveal the electron accumulation regions induced by lattice distortion as high-activity sites, thereby driving the augmented HER performance of HESe₂. This work presents a universal strategy for boosting the basal plane activity of layered materials through unique lattice distortion effect.