Functionalized tetrahedral silsesquioxane cages for hydrogen storage. (13th November 2020)

• Record Type: Journal Article
• Authors: Konda, Ravinder; Deshmukh, Amol; Kalamse, Vijayanand; Chaudhari, Ajay
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 56(2020)
• Page Start: 32157
• Page End: 32167
• Publication Date: 2020-11-13
• Subjects: Density functional theory -- Tetrahedral silsesquioxane -- DOS -- Hydrogen storage; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.08.151
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: The hydrogen storage capacity of functionalized Tetrahedral Silsesquioxane (H4 Si4 O6 ) cages is obtained using density functional theory (M062X) and second order Møller-Plesset (MP2) method with 6-311++G∗∗ basis set. We labelled Tetrahedral Silsesquioxane (H4 Si4 O6 ) as 'TS'. We replaced four hydrogen in TS one by one with C2 HBe or C2 HTi group and labelled as TSR1 M1, TSR2 M2 TSR3 M3 and TSR4 M4 where RM can be either C2 HBe or C2 HTi. In TSRM when one hydrogen in a cage is replaced by C2 HBe or C2 HTi maximum of two and five hydrogen molecules, get adsorbed per Be and Ti atom respectively with respective H2 capacity of 1.61 and 3.42 wt %. H2 uptake capacity of TSRm Mm (m = 1, 2, 3 and 4) has increased extensively when all the hydrogen in cage are replaced either C2 HBe or C2 HTi. TSR4 M4 with RM = C2 HTi can adsorbs maximum of 20H2 molecules with highest H2 uptake of 7.46 wt % among all the studied complexes. Calculated Gibbs free energy corrected H2 adsorption energies show that adsorption of H2 molecules on all the complexes is thermodynamically favourable. The desorption temperature for the complexes were calculated by using the van't Hoff equation. Calculated interaction energies show that H2 molecules interact strongly with Be atom than Ti atom. The molecular dynamics (MD) simulations have also been performed using atom centered density matrix propagation (ADMP) at ambient conditions. Interaction of hydrogen molecules and the metal atom is confirmed through the density of states (DOS) plot. Highlights: Functionalized Tetrahedral Silsesquioxane (TS(RM)n, RM=C2 HBe/C2 HTi) for H2 storage. TS(C2 HTi)4 cage can adsorbs max. of 20 H2 molecules with highest uptake of 7.46 wt%. TS(C2 HBe)4 cage can adsorbs max. of 8 H2 molecules with highest uptake of 4.47 wt%. Thermodynamically favourable H2 adsorption on all the TS(RM)n complexes.