Hydrangea-like high-entropy material (FeNiCoMnMo)S₂ as highly efficient bifunctional electrocatalyst for overall...

The tunability of elemental composition in high-entropy materials (HEMs) offers a wealth of active sites, positioning them as a significant class of materials for water-splitting electrocatalysis. HEMs are characterized by four core effects that enhance electrocatalytic activity and ultimately contribute to exceptional long-term durability. In this study, high-entropy layered double hydroxides (FeNiCoMnMo-LDH) are successfully synthesized using a hydrothermal method, followed by a transformation into high-entropy disulfides, (FeNiCoMnMo)S₂, via chemical vapor deposition. The overpotentials of disulfides decrease with increasing numbers of metal components, with the five-element HEM demonstrating the most superior electrochemical performance. The lowest required overpotentials of 87 and 226 mV at 10 mA cm^-2 as well as those of 344 and 346 mV at a high current density of 800 mA cm^-2 are achieved for (FeNiCoMnMo)S₂ synthesized using 300 °C ((FeCoNiMnMo)S₂-300) respectively for hydrogen and oxygen evolution reactions. In the two-electrode system using FeCoNiMnMo)S₂-300 for overall water splitting, cell voltages of 1.54 and 1.97 V are respectively required to achieve the current density of 10 and 500 mA cm^-2. Additionally, at a constant applied potential, the system sustains a current density of 10 mA cm^-2 for 100 h, which demonstrates the excellent bifunctional performance of (FeCoNiMnMo)S₂ in water-splitting applications.