The future of hydrogen economy: Role of high entropy alloys in hydrogen storage

High entropy alloys (HEAs) are distinguished for their unique properties, particularly in hydrogen storage applications. Their diverse compositions offer significant potential for developing advanced materials, crucial for the hydrogen economy. Metal hydrides are dependable for long-term hydrogen storage due to their high densities and safety, yet they often face limitations in capacity or require unfavorable conditions for reversibility. The current review examines the revolutionary developments in HEAs, focusing on the critical and reliable categories within this material class. It highlights their high hydrogen uptake and excellent reversibility under mild conditions. The review explores theoretical and compositional design approaches, thermodynamic considerations, and alloy preparation, offering insights into performance and challenges. Notably, the Ti-V-Cr-Mn-Mo-Ce alloy, synthesized via vacuum arc melting and Ce doping, exhibits a hydrogen storage capacity of 3.60 wt%, absorbs hydrogen rapidly within 40 seconds with 1 wt% Ce doping, and has an enthalpy change for desorption of -17.96 kJ/mol H2. The exceptional performance of HEAs, emphasizes their role in advancing sustainable hydrogen storage solutions and addressing key challenges, thus contributing significantly to the hydrogen economy.