PR_Pri-1

[Audio] In silico study of Hydrogen storage by Lithium decorated Planar tetra Coordinate Hydrogen and Fluorine Cluster INTRODUCTION: In a constantly evolving landscape where the demand for energy is on the rise there is an urgent quest for cleaner and sustainable alternatives. A sustainable and environmentally friendly energy source serves as a robust substitute for fossil fuels which are notorious for their pollution. Choosing renewable alternative helps mitigate the negative environment impacts associated with traditional pollutants-heavy energy sources. The transition to a clean energy economy represents a transformative shift from the current state of the world promising revolutionary changes in how we produce and consume energy.One such promising green fuel is hydrogen gas which is much safer renewable economical and abundant in nature. While hydrogen gas is deemed a promising alternative fuel its widespread adoption faces a hurdle due to inadequate storage materials. Due to its notably low volumetric energy density hydrogen gas necessitates large storage containers. Thus storing hydrogen on vehicles presents a formidable challenge requiring innovative solutions for on-board storage in transportation. Additionally it possesses one of the lowest minimum ignition energies underscoring the need for scrutiny of potential ignition sources to ensure safety in handling and storage. Given its extremely low density hydrogen gas has a heightened propensity to leak into the atmosphere which concerns regarding its safe storage. To be suitable for domestic and automotive applications an ideal storage material must meet specific criteria including high gravimetric and volumetric densities easy accessibility rapid kinetic behaviour for both adsorption and desorption favourable enthalpies for hydrogen adsorption and desorption low molecular weight and cost-effective recharging capabilities. As per the U-S Department of Energy guidelines a hydrogen storage system is expected to achieve a gravimetric density of 5.5wt% by the year 2025. Additionally the system should be functional within a temperature range spanning from -40 degrees celsius to 85°C emphasizing the criteria for both storage efficiency and operational adaptability..

[Audio] Storage System Gravimetric Density Volumetric Density Cost ($/kWh) Targets System (wt%) System (MJ/L) 2019 4.2 2.9 15 2020 4.5 3.6 10 Ultimate 6.5 6.1 8 The storage of hydrogen gas is possible in two ways :chemical storage as well as physical storage. Chemical storage:Chemical hydrogen storage materials are substances where hydrogen is tightly bonded either in solid or liquid form. When these materials release hydrogen it’s usually accompanied by heat or requires a small amount of energy input. Recharging them typically involves using methods other than just applying pressure. While they’re great for one-time specialised uses using them for widespread transportation would mean the spent material needs to be recharged off-site which currently make the overall cost higher. Plus predicting how hydrogenis released from these compound can be tricky due to their complex reaction pathways. ( explain with figure). Physical storage:Physical storage of hydrogen gas involves storing it in it elemental form typically either compressed for liquefied.It involves weak interaction between host molecule and H2 via van der Waals force long range attraction force as well as short range repulsive forces. In compressed hydrogen storage the gas molecules are held together by these weak intermolecular forces within the container. Similarly in liquefied hydrogen storage the weak interaction plays a role in keeping the hydrogen molecules close together in their liquid state. This contrasts with chemical storage methods where hydrogen is covalently bonded to other elements in compounds..

[Audio] This has stimulated a quest for materials that meet the specified criteria addressing the need for suitable substance capable of fulfilling the requirements for hydrogen storage systems where the interaction between host molecule and H2 lies between chemical and physical storage to achieved the reversibility criteria. Literature Survey: In earlier decade various carbon-based nanostructures metals organic frameworks nanotube metal-based hydrides for hydrogen storage have been explored. The challenge in achieving improved gravimetric and volumetric hydrogen storage lies in finding materials that not only provide efficient binding to securely store H2 but also possess an appropriate binding energy for the controlled release of hydrogen making the storage process reversible. This has proven to be demanding task. Meiyan and others showed how H2 interact with Li doped charged single walled carbon nanotube. V Kalamse and others worked on hydrogen storage in various organometallic complex. In several studies the metal incorporation in the host molecule improves the storage capacity of hydrogen. B Sakuntina and others Showed Mg-based hydrides stand as promising candidate for competitive hydrogen storage with reversible hydrogen capacity up to 7.6 wt% for on-board applications. However these studies still lack in fulfilling the required criteria. As well as the substantial mass of transition metals Is typically undesirable when aiming for high gravimetric density. Therefore there is considerable interest in exploring materials that are lightweight as an alternative seeking to optimize the storage efficiency without the drawbacks associated with heavier elements. Recently M K Dash and others using first principle calculation studied hydrogen adsorption of different Li doped five membered aromatic heterocyclic systems. Li-decorated materials have shown promise for reversible hydrogen storage. Li-decorated T-BN monolayers have an ultrahigh hydrogen adsorption capacity of 12.31 wt% with adsorption strength of 0.245–0.315 eV/H2 almost twice the U S D-O-E target. Li-decorated NP monolayers can achieve a hydrogen storage.

[Audio] gravimetric density of 5.5 wt% with stable structural stability. Li-functionalized PCP222 can adsorb up to 15H2 molecules with an average adsorption energy of 0.145 eV/5H2 reaching a hydrogen uptake capacity of 8.32 wt%. Li and Sc doped C-8-N-8 cages can adsorb 5H2 molecules with an average hydrogen adsorption energy of 0.187 and 0.291 eV/H2 achieving hydrogen storage capacities of 8.32 wt% and 6.33 wt% respectively]. Li-decorated N-doped Me-graphene can achieve a maximum adsorption number of 8 hydrogen molecules and a gravimetric density of 8.57 wt%. These findings suggest that Li-decorated materials have the potential for reversible hydrogen storage. In this work we want to fulfil the various issue related with hydrogen storage mainly to improve gravimetric density in the highest point by using some clusters. We choose Li decorated clusters for such purpose because the Li has low molecular weight and hence it may be a good material for better gravimetric density. In very recent Guha et. al design planar tetracoordinate hydrogen and fluorine cluster [ref] which is decorated by Lithium atom which is properly studied clusters. This clusters may be a promising 2D materials for storage of hydrogen in near future. Result and discussion: The adsorption of hydrogen molecules onto the planar clusters relies primarily in van der waals interactions with dispersion playing a crucial role in bonding. To understand this interaction all molecules were fully optimised using computational methods at B3LYP-D3(B-J---) level wth the def2TZVP basis set. Harmonic vibrational frequency calculations were performed to analyse the nature of stationary points. The calculated energies account for zero point and thermal corrections. Importantly all optimised structures were confirmed to be at local minima as indicated by the presence of real values in the Hessian matrix. This comprehensive computational approach allows for a detailed understanding of the hydrogen adsorptions process on planar clusters..

220 : 219 2.19 ptH-H2 239 2.35 237 2.14 ptH-10H2 ptH-5H2 236 2.12 ptH-15H2.

[Audio] CompoundꝬ(r)V(r)G(r)H(r)∇2ρ(r)ptF-H20.009-0.0030.0040.0600.0190.034-0.0550.0680.0230.325ptF-2H20.009-0.0040.0040.0010.019ptF-3H20.009-0.0040.0040.0590.0190.009-0.0040.0040.0590.0190.009-0.0040.0040.0570.019COMPOUNDꝬ(r)V(r)G(r)H(r)LapptH-H20.007-0.0060.0030.0590.0150.007-0.0060.0080.0080.0410.006-0.0030.0040.0290.017ptH-2H20.013-0.0060.0060.0950.0250.014-0.0070.0070.1030.031PtH-3H20.013-0.0050.0060.0170.0250.012-0.0050.0050.0960.0220.013-0.0050.0060.1180.025.

[Audio] complexes Bond Desorpt Adsorption H2 Freq Gravimetric distance ion energy (H-H) density(w%) from the energy (upto15H2) cluster ptH-H2 2.19(Li-H) 0.03 -0.03 0.752 4228.36 42.9 ptH-5H2 2.21(Li-H) 0.09 -0.03 0.753 4274.99 ptH-10H2 2.05(Li-H) 0.03 -0.01 0.753 4281.31 ptH-15H2 2.22(Li-H) 0.08 -0.01 0.752 4283.63 ptH-16H2 2.22(Li-H) 0.09 -0.01 0.752 4286.06 ptF-H2 2.34(Li-H) 0.03 -0.03 0.750 4270.65 34.88 ptF-5H2 2.34(Li-H) 0.02 -0.01 0.750 4271.95 ptF-10H2 2.34(Li-H) 0.03 -0.01 0.750 4273.74 ptF-15H2 2.36(Li-H) 0.02 -0.01 0.750 4281.94 ptF-16H2 2.36(Li-H) 0.03 -0.01 0.750 4283.66.

[Audio] Adsorption–Desorptionanalysis:Theprocessofhydrogenbindingtothemostclusterisexaminedstepbysteptodeterminethetypeofadsorptionaccurately.Thismeansthatresearchersanalyzehowhydrogeninteractswiththeclusterinasystematicway examiningeachstageofthebindingprocesstounderstandwhethertheadsorptionisphysical(suchasphysisorptionorchemisorption)orchemicalinnature.AttheB3LYP-D3(B-J---)levelwiththedef2TZVPbasisset theH-Hbondlengthisobservedtobestretchedfromtheusual0.744A°distanceofanH2molecule.Theelectropositivenatureoflithium(Li)atomscreatesanattractivezonearoundtheplanarclusterstheyform.Thisattractivezoneisstrongenoughtopolarizenearbymolecularhydrogen(H₂).Duetothispolarization molecularhydrogenbindstothelithiumatomsinanon-covalentmanner meaningthebondingdoesnotinvolvethesharingofelectronsasincovalentbondsbutratherweakerinteractionslikevanderWaalsforces.Thebindingenergies knownasEads forthisinteractionhavebeencalculatedtofallintherangethatissignificantbecauseitisbetweenphysisorption(wheremoleculesadheretosurfacesthroughweakvanderWaalsforces)andchemisorption(wheremoleculesformstrongchemicalbondswiththesurface).Thisintermediateenergyrangesuggeststhatthehydrogencanbeadsorbedanddesorbedrelativelyeasily makingthematerialsuitableforreversiblehydrogenstorage.Thisisparticularlyimportantforapplicationswherehydrogenneedstobestoredandreleasedundernormalconditionsoftemperatureandpressure.Tofurtherexaminetheeasewithwhichhydrogencanbedesorbed(released)fromtheseclusters desorptionenergies(Edes)werecalculatedforeachsuccessivereleaseofhydrogen.TheEdesvaluesshowedthatdesorptionalsooccurswithinamanageableenergyrange supportingthereversibilityofthehydrogenstorage.Avisualcomparisonoftheseadsorptionanddesorptionenergies illustratingtheefficiencyandreversibilityofhydrogenstorageintheseLi-basedclusters..

[Audio] Topological analysis: The topological analysis of electron density of the above clusters were done in Multiwfm programme at B3LYP/def2TZVP level . Here the topological analysis is done using Bader’s quantum theory of atoms in molecules (QUTAIM) where characterisation of atomic interaction of bare complexes with that of hydrogen molecules is done. The place where the surface of one atom meets the surface of another atom is known as the atomic interaction line. This concept introduces the idea of bonding through path way called bond path and a specific point along that pathway called bond critical point. Essentially it’s where atoms come together forming bonds and these points and paths help us understand how those bonds are created and maintained. At the bond critical point there’s a minimal amount of electron density present indicating a weak interaction between the cluster and H2 molecules. This suggests that bond between the cluster and H2 molecules is not very strong emphasizing the relatively weak nature of the interaction. The laplacian of electron density ∇2ρ(r) reveals minimal charge concentration between the Li and H2 molecules suggesting a closed shell interaction. This means that the electron density around these molecules is relatively stable and evenly distributed. Similarly the electron localisation function (E-L-F--) plot indicates that there is very little accumulation of localised electrons in the region where the lithium atom and hydrogen molecule interact. This further supports the idea of a closed shell interaction indicating that the electrons are not strongly localised in this region. Overall the electronic property study indicates that the interaction between the H2 molecule and the Li centre is of a non covalent nature . This means that the bonding between them does not involve sharing of electrons pairs but rather involves weaker interactions. Such as van der waals forces or electrostatic attraction. The positive value of thr laplacian of electron density [∇2ρ(r)] indicates a close shell interaction of the H2 molecules. This means that the electron density is relatively stable and well distributed around the hydrogen molecules. Moreover the laplacian of the electron density is connected to the local kinetic energy density V(r) as outlined by Bader’s theorem. This theorem establishes a relationship between the distribution of electrons and the kinetic and potential energy densities at a given point in space. For a stable stationary state the local kinetic energy density G(r) and local potential energy density V(r) are positive and negative respectively . this indicates that there’s movement and energy associated with the electrons while the potential energy is associated with the attractive forces.

[Audio] between the electrons and the nucleus. Furthermore when we look at the ratio of the negative kinetic energy density at the bond critical point [-G(r)] to the potential energy density at the point [V(r)] if the ratio is greater than 1 it suggests that the kinetic energy dominates around the bond critical point. Additionally the presence of positive local electronic energy density H(r) further confirms the existence of electrostatic interaction indicating attraction between the electrons and the positively charged nucleus. Bonding analysis; In the ptH-H₂ and ptF-H2 complexes the distance between the lithium (Li) atom and the hydrogen (H) atoms ranges from 2.19 Å to 2.22 Å and 2.34 to 2.36 while the distance between the two hydrogen atoms (H-H) extends slightly from the normal bond length of 0.744 Å to between 0.750 Å and 0.752 Å. These measurements were obtained using the B3LYP/def2TZVP computational level. Additionally the H-H bond stretching frequencies have decreased notably with calculated values ranging from 4228.1 centimeters⁻¹ to 4283.6 centimeters⁻¹ which are lower than the stretching frequency of a free H₂ molecule which is 4438.1 centimeters⁻¹. The elongation of the H-H bond and the reduction in its stretching frequency within the Li4B2−(H2)n complexes indicate that a significant amount of charge is being transferred from the H-H σ bond to the lithium center. This charge transfer weakens the H-H bond causing it to stretch and vibrate at a lower frequency than in a free H₂ molecule..

[Audio] OfficeofEnergyEfficiency&RenewableEnergy.Energy(accessedNov.19 2024).1M.Ni L.Huang L.GuoandZ.Zeng Int.J.HydrogenEnergy 2010 35 3546–3549.2 volts.Kalamse N.WadnerkarandA.Chaudhari J.Phys.Chem.C 2010 114 4704–4709.3B.Sakintuna F.Lamari-DarkrimandM.Hirscher InternationalJournalOfHydrogenEnergy 2007 32 1121–1140M K Dash S.Sinha H S Das G C De S.GiriandG.Roymahapatra SustainableEnergyTechnol.Assess. 2022 52 102235.Yong Y.;Hou Q.;Yuan X.;Cui H.-L.;Li X..UltrahighCapacityandReversibleHydrogenStorageMediaBasedonLi-decoratedT-BNMonolayers.2023 72.Jiang M.;Xu J.;Munroe P.;Xie Z..First-principlesCalculationsofLi-decoratedDiracSemimetalNPMonolayerasaPotentialReversibleHydrogenStorageMedium.2023 35.Sahoo R K ;Sahu S..ReversibleHydrogenStorageinLiFunctionalized[2 2 2]paracyclophaneatCryogenictoRoomTemperatures:AComputationalQuest.2023.Sahoo R K ;Sahu S..ReversibleHydrogenStorageCapacityofLiandScDopedNovelC8N8Cage:InsightsfromDensityFunctionalTheory.2022 46(15).Wu G.;Gao S.;Zhang C.-.ling.;Zhang X.;Hao J.;Jia B.;Guan X..PotentialHydrogenStorageMaterialsfromLiDecoratedN‐dopedMe‐graphene.2022 46(15)..