Investigating Ti-based hydrides double perovskites Li2TiXH6 (X= Fe and Co) for hydrogen storage applications

초록

In this article, we employed Density Functional Theory (DFT) based computational techniques to calculate structural, optoelectronic, gravimetric hydrogen storage capacities (GHSCs), and mechanical properties of halide double perovskites for their potential applications in green energy production. The structural stability of Li2TiFeH6 and Li2TiCoH6 is highlighted by negative values of formation enthalpies i.e.,-0.221 and-0.224 eV/atom, respectively. The absence of energy band gaps in the electronic band structures of Li2TiXH6 (X = Fe and Co) is evidence for their metallic nature. The calculated values of GHSCs for Li2TiFeH6 and Li2TiCoH6 are 4.89 and 4.77 Cwt%, respectively. The imaginary component of dielectric function epsilon 2(omega) spectra reveal that Li2TiXH6 (X = Fe and Co) absorbs maximum incident photons in infrared region, however, absorption in near UV region is also considerable. These values show that these hydrides can be employed for optoelectronic gadgets operating in UV and infrared regions. The calculated elastic constants satisfy the Born stability criteria indicating the mechanical stability of Li2TiXH6 (X = Fe and Co). The calculated values of Pugh's ratio B/G are 0.83 and 0.88 for Li2TiFeH6 and Li2TiCoH6, respectively, revealing their brittle nature. The values of Cauchy pressure C-y reveal that Li2TiXH6 (X = Fe and Co) possess covalent bonding. These properties indicate the potential of investigated novel hydrides Li2TiXH6 (X = Fe and Co) for hydrogen fuel cell manufacturing to address current global energy crisis.

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