Controlled Synthesis of High-Entropy-Material Nanoparticles. Optimization of Traditional and Creation of Innovative Strategies

Abstract—In the last decade, the diversity of high-entropy materials (HEMs) has increased dramatically, including the expansion of investigations in the field of amorphous, nano-, and heterostructures. Interest in nanoscale HEAs is primarily related to their potential applications in various fields, such as renewable and green energy, catalysis, hydrogen storage, and surface protection. The development of nanotechnologies made it possible to develop an innovative design of nanoscale HEAs with fundamentally new structures having unique physical and chemical properties. The problems of controlled synthesis with precisely specified parameters of chemical composition, microstructure, and morphology are solved. Traditional technologies, such as rapid pyrolysis, mechanical alloying, magnetron sputtering, electrochemical synthesis, etc., are being modified. In addition, innovative synthesis technologies, such as carbothermal shock and controlled hydrogen spillover, have appeared. This review analyzes the methods of synthesizing nanoscale HEAs for various applications that have been developed in the last six–seven years. Most of them result from the modification of traditional methods, and another group of techniques presents innovative solutions stimulated and inspired by the HEA phenomenon.