Quantum chemical investigation of the electronic, optoelectronic, X-ray spectroscopy, and hydrogen storage capacity of AHfO3/BAgO3 (A = Cs, Ag; B = Hf, Cs) perovskite materials

This study focuses on investigating the structural, electronic, mechanical, X-ray spectroscopy, optoelectronic, and the hydrogen storage properties of AHfO3 and BAgO3 (A = Cs, Ag; B = Hf, Cs) perovskites using the first-principles density function theory (DFT) approach. The optimized compounds reveals that the Lattice constant as well as total energy data of AHfO3 and BAgO3 (A = Cs, Ag; B = Hf, Cs) which was observed to be in the order of CsAgO3 > CsHfO3 > AgHfO3 > HfAgO3, has the influence of cation size and position on the lattice constant. The PDOS plot of AgHfO3 shows that Hf-5p and O-2p orbital make significant contribution to the valence band, whereas the conduction band is formed from the electronic contributions of Ag-4d and O-2p states. For CsHfO3, the PDOS plot reveals that the valence band below the Fermi energy level results from the 5p and 2p electrons of Hf and O atoms, respectively. On the other hand, the major contributions for the conduction band formation are from the 4d – Ag and 2p – O orbitals. Additionally, the dielectric function, refractive index, and extinction coefficient were calculated in the energy range of 1 – 12 eV which shows fascinating optical properties. The structure when modified by hydrogenation to AgHfH3, CsHfH3, CsAgH3, and HfAgH3 showed results suggesting their good hydrogen storage characteristics. The estimated desorption temperature of CsAgH3, HfAgH3, CsHfH3 and AgHfH3 are in the range of 351, 344, 384 and 361 °K respectively while the formation energy was observed to be in the range of −44.995 to −50.277 KJ.mol−1.H2.