Strain Modulated Hydrogen Storage Aspects, Optoelectronic, and Thermoelectric Energy Harvesting in a Newly Synthesized BaSiH6

Abstract

Hydrogen is widely acknowledged as a highly effective potential solution to meet the steadily increasing demand for clean and environmentally friendly energy, where hydridosilicates emerge as an efficient hydrogen storage (HS) material. Therefore, BaSiH6 (BSH) is examined through first-principles calculations to assess its HS potential under strain. The calculated formation enthalpy (∆H_f) of -40.86 kJ/mol•H_2 for the unstrained (unstr.) system aligns excellently with the ideal value of -40 kJ/mol•H 2 even for considered strained levels. The calculated hydrogen desorption temperature (T_des.) of 292 K (unstr. value) and strained values hold an excellent range of 233-333 K. Besides, a high gravimetric HS capacity of 3.53% is achieved and the volumetric HS capacity improves to 11%/17% under -5% biaxial/hydrostatic strain. Moreover, ab-initio molecular dynamics simulations confirm the thermal stability of the system at 300 K, as no spontaneous decomposition was observed. Additionally, all the structures are mechanically stable and exhibit ductile behavior.The ionic bonding in the structure is supported by electron density analysis, which reveals predominantly ionic Ba-H and covalent Si-H character. Interestingly, systems exhibit suitable energy gaps and substantial visible-light absorption, which enhances their utilization for a capable solar energy conversion process. Finally, it is found that tensile strains reduce the lattice thermal conductivity due to improved phonon scattering, resulting in a higher figure of merit and positive Seebeck coefficient, making it a hot candidate for converting waste heat into electricity. Hence, the present study suggested a strong potential of the BSH for HS, optoelectronic, and energy harvesting applications.