First-principles study of structural, electronic, optical, and hydrogen storage properties of Li ₂ TiXH ₆ (X=Cr,Mn) hydrides for an advanced hydrogen storage system

The world is moving toward clean and sustainable energy, which makes it even more important to find good ways to store hydrogen. Metal hydrides are especially appealing among the several options since they have high volumetric and gravimetric densities. In this research, we utilize first-principles Density Functional Theory (DFT) computations via the CASTEP code to methodically examine the structural, electrical, optical, and hydrogen storage characteristics of Li 2 TiXH 6 (X [Formula: see text] Cr, Mn) hydrides. Our findings validate the structural stability of these compounds, which crystallize in the cubic Fm-3m space group, and elucidate their metallic characteristics as demonstrated by band structure and density of states investigations. Optical investigations also show that they absorb and conduct well in the low-energy range, which confirms that they could be useful for energy-related uses. The calculated hydrogen storage capabilities are 5.05[Formula: see text]wt.% for Li 2 TiCrH 6 and 4.93[Formula: see text]wt.% for Li 2 TiMnH 6 , which is close to the U.S. DOE goal of 5.5[Formula: see text]wt.%. These results offer the inaugural full theoretical understanding of Li 2 TiXH 6 hydrides, designating them as prospective contenders for next-generation solid-state hydrogen storage devices.