Computational screening of Ti-Based YTi3H8 (Y = Na, K and Rb) hydrides for efficient solid-state hydrogen storage system

Abstract

There has been a lot of recent interest on hydrogen storage due to the fact that hydrogen may be utilized as an energy source. Evaluation of newly synthesized compounds' hydrogen storage capabilities has dominated studies on hydrogen storage applications. For the first time, density functional theory (DFT) calculations have been run to study the unique characteristics and hydrogen storage capabilities of the YTi₃H₈ (Y = Na, K, and Rb) compounds. The lattice constants for the compounds being studied are 4.85 Å for RbTi₃H₈, 4.74 Å for KTi₃H₈, and 4.54 Å for NaTi₃H₈ when optimized in the cubic phase. These hydrides have negative formation enthalpy, which means they are thermodynamically stable. High gravimetric hydrogen storage densities of 4.62 % for NaTi₃H₈, 4.23 % for KTi₃H₈, and 3.40 % for RbTi₃H₈ make YTi₃H₈ (Y = Na, K, and Rb) a promising candidate for hydrogen storage. In addition, the electronic properties of these compounds lend credence to their metallic properties. Furthermore, these compounds satisfy the Born stability conditions as shown by examination of the mechanical properties obtained from elastic constants, such as Pugh's ratio and Young's modulus. While both NaTi₃H₈ and KTi₃H₈ hydrides are brittle, Pugh's ratio and Cauchy pressure show that KTi₃H₈ hydride is ductile. The mechanical stability, high hydrogen storage capacity, and metallic nature of YTi₃H₈ (Y = Na, K, and Rb) indicate that they might be used in solid-state hydrogen storage devices. Fuel cell technologies, hydrogen-powered cars, and stationary energy storage applications can benefit from their stability and high hydrogen content, making them potential candidates for sustainable hydrogen energy solutions.