Mechanochemical Route to Novel High Entropy Materials for Rechargeable Batteries and Water Splitting Electrocatalysis

Owing to the significantly growing consumption of fossil fuels and emerging environmental concerns, new sustainable energy sources and innovative energy storage solutions are gaining significance in contemporary society. Hydrogen is being considered as a promising clean and renewable energy source, but efficient production to meet demand remains a challenge. Electrocatalytic water splitting is a potential pathway, however, its practical realization requires the development of stable, low-cost, and highly active catalysts. Furthermore, in order to optimize the harnessing of renewable energy sources, particularly those with inherent variability, there is a burgeoning requirement for energy storage systems, notably exemplified by the prominence and extensive investigation of lithium-ion batteries (LIBs) in scientific discourse. Among the various components of these devices, the electrode material is a crucial part that greatly affects the performance and cost of rechargeable batteries. Frequently, the enhancement of energy technologies necessitates the discovery and development of optimized materials, underscoring the criticality of exploring novel substances for energy conversion and storage purposes. ... mehrIn this context, catalysts and electrode materials hold particular importance, and investigating their composition-structure-property relationships becomes indispensable for facilitating future advancements in the field.
In recent years, high entropy materials (HEMs) have emerged as a promising class of materials for various applications, due to their distinctive structural features, customizable chemical composition, and resulting adjustable functional properties. The application of the high entropy concept to the energy field also offers opportunities for the design and the synthesis of novel materials with unprecedented properties.
In this dissertation, a novel mechanochemical method was successfully applied to synthesize HEMs, including high entropy oxides, oxyfluorides, and sulfides of different compositions and structures, containing thermally unstable or air-sensitive ions. The structural and chemical details of the prepared HEMs are studied by various techniques of X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Mössbauer spectroscopy and X-ray photoelectron spectroscopy (XPS). By this facile one-step synthesis, a series of HEMs were designed, prepared and investigated as electrode materials for LIBs and electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). These HEMs, particularly high entropy sulfides, showed exceptional capabilities in rechargeable batteries and water electrolysis, highlighting the potential and capacity of customized HEMs for various future applications.