A universal, green, and self-reliant electrolytic approach to high-entropy layered (oxy)hydroxide nanosheets for efficient electrocatalytic water oxidation.

The development and exploration of high-entropy materials with tunable chemical compositions and unique structural characteristics, although challenging, have attracted increasingly greater attention over the past few years. Here, we report a universal and green method to prepare high-entropy layered (oxy)hydroxide (HE-LH) nanosheets under ambient conditions. This method is based on a self-reliant electrochemical process, utilizing only low-cost metal foils and electrolytes as reactant, with no need of involving extra alkali salts and/or organic reagents. Importantly, the composition of HE-LH nanosheets is widely tunable by simply adjusting the combination of metal foils. As a representative example, quinary layered (oxy)hydroxide (CoFeNiCrV-LH) nanosheets are rationally designed, which exhibit superior electrocatalytic activity and long-term durability towards the electrocatalytic oxygen evolution reaction, outperforming both CoFe layered double hydroxides and most previously reported transition-metal-based electrocatalysts. Comprehensive characterization and analysis reveal that the high-entropy effects play a significant role in forming the defect-rich, low-crystalline microstructures, along with large specific surface areas and optimized electronic configurations, thus enabling the boosted electrocatalytic performance. This electrochemical synthetic approach is generally applicable to the scalable synthesis of diverse HE-LH materials towards versatile promising applications.