Sub-1 nm High-Entropy Materials for Electrochemical Applications

Sub-1 nm high-entropy materials (SNHEMs) have garnered significant attention for their exceptional catalytic activity and stability in electrocatalysis and energy storage. Compared with conventional nanomaterials, SNHEMs effectively mitigate aggregation, and they offer higher exposure of active sites than traditional high-entropy materials (HEMs). These advantages arise from their ultrahigh specific surface area, abundant active sites, and tailorable electronic/band structures. As SNHEMs emerge as a cutting-edge field for advanced energy materials, a comprehensive review of this class of materials is imperative. Herein, we summarize the primary controllable synthesis strategies of SNHEMs; systematically discuss recent advances in pivotal electrocatalytic reactions, such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR); and elaborate on their applications in energy storage devices, including sodium-ion batteries (SIBs), lithium-oxygen batteries (LOBs), and zinc-air batteries (ZABs). Finally, we highlight the current research challenge and outline promising directions for future development.