Tuning the hydrogen storage properties of MOF-650: A combined DFT and GCMC simulations study

Combined density functional theory and grand canonical monte Carlo (GCMC) calculations were performed to study the electronic structures and hydrogen adsorption properties of the Zn-based metal-organic framework MOF-650. The benzene azulenedicarboxylate linkers of MOF-650 were substituted by B atoms, N atoms, and boronic acid B(OH)₂ linkers, and the Zn atoms were substituted by Mg and Ca atoms. The calculated electronic densities of states (DOSs) of MOF-650 showed that introduction of B atoms reduces the band gap but damages the structure of MOF-650. Introduction of single N bonds cannot provide active electrons to attract H₂ molecules. Thus, substitutions of B and N into MOF-650 are not suggested. B(OH)₂ substitute in MOF-650 decreased its band gap, slightly improved its hydrogen storage ability and made H₂ molecules more intensively distributed besides organic linkers. GCMC calculations were carried out by estimating the H₂ storage amount of the pure and modified MOFs at 77 and 298 K and from 1 bar to 20 bar. B(OH)₂ linker and Mg/Ca co-doped MOF-650 showed increased H₂ adsorption by approximately 20 wt%. The adsorption of H₂ around different bonds showed the order N–C < C = C < B–C < C–O < B–O.     

Bimetal metal-organic framework hollow nanoprisms for enhanced electrochemical oxygen evolution

Carboxylate-based metal-organic frameworks (MOFs) have emerged as promising electrocatalyst candidates for the water splitting and metal-air batteries. Hierarchical porous structure and redox-active metal centers with unsaturated coordination sites in MOFs facilitate the enhanced catalytic activity of oxygen evolution reaction (OER). Herein, uniform hollow structured Fe-free bi-metal (Co, Ni) MOF-74 nanoprisms are successfully synthesized using a solvothermal method and (Co₁Ni₁)₃(OH)(CH₃COO)₅ as the sacrificial templates, where Co and Ni are the metal nodes and 2,5-dihydroxyterephthalic acid (H₄DOBDC) serves as the organic ligand. At an overpotential of 300 mV, CoNi MOF-74 shows a high electrocatalytic activity towards OER in 0.1 M KOH, where the current density is 10 mA cm^?2 and the Tafel slope is 65.6 mV dec^?1. Meanwhile, CoNi MOF-74 is durable that sustains in alkaline for 100 h with 83.25% retention of current density. The improved catalytic activity can be associated with the in-situ generated amorphous Ni–Co (oxy)hydroxide, as well as the electron transfer from Ni²⁺ to Co²⁺. This work elucidates the potential application of MOF materials as efficient electrocatalysts for OER.     

Nanoscale cobalt doped carbon aerogel: microstructure and isosteric heat of hydrogen adsorption

The incorporation of nanoscale Co particles (with sizes from a few nanometres) into porous carbon aerogels (CAs) was investigated. Elemental maps of the nanoscale metal particles embedded within CA were obtained using energy filtered transmission electron microscopy. The microstructure of Co doped carbon aerogels was further investigated using small angle X-ray scattering and nitrogen adsorption at 77 K. The isosteric heat of adsorption (Qst) was investigated as a function of hydrogen uptake at temperatures from 77 K to 110 K over the pressure range of 0-0.25 MPa. The isosteric heat of adsorption at low H₂ concentration for Co doped CA (9.0 kJ mol⁻¹) was found to be higher than for pure CA (5.8 kJ mol⁻¹).     

A model study of effect of M = Li,Na, Be,Mg, and Al ion decoration on hydrogen adsorption of metal-organic framework-5

The effect of light metal ion decoration of the organic linker in metal-organic framework MOF-5 on its hydrogen adsorption with respect to its hydrogen binding energy (ΔB.E.) and gravimetric storage capacity is examined theoretically by employing models of the form MC₆H₆:nH₂ where M = Li⁺, Na⁺, Be²⁺, Mg²⁺, and Al³⁺. A systematic investigation of the suitability of DFT functionals for studying such systems is also carried out. Our results show that the interaction energy (ΔE) of the metal ion M with the benzene ring, ΔB.E., and charge transfer (Q_trans) from the metal to benzene ring exhibit the same increasing order: Na⁺ < Li⁺ < Mg²⁺ < Be²⁺ < Al³⁺. Organic linker decoration with the above metal ions strengthened H₂-MOF-5 interactions relative to its pure state. However, amongst these ions only Mg²⁺ ion resulted in ΔB.E. magnitudes that were optimal for allowing room temperature hydrogen storage applications of MOF-5. A much higher gravimetric storage capacity (6.15 wt.% H₂) is also predicted for Mg²⁺-decorated MOF-5 as compared to both pure MOF-5 and Li⁺-decorated MOF-5.     

Interaction of H2 with fragments of MOF-5 and its implications for the design and development of new MOFs: A computational study

The interaction energies (IEs) of H₂ and various organic ligands have been computed using coupled-cluster method with singles, doubles, and noniterative triples (CCSD(T)) at the complete basis set (CBS) limit. The density fitting-density functional theory-symmetry adapted perturbation theory (DF-DFT-SAPT) approach has been used to probe the nature of interaction between H₂ and organic linkers. It has been found that dispersive interaction predominantly stabilizes the intermolecular complex formation of H₂ on a variety of organic linkers. Furthermore, H₂ binding affinity of inorganic connectors is improved by partial isomorphic substitution of Zn by different metal ions such as Fe, Co, Ni and Cu. A new modified metal-organic framework (MOF-5 M) has been designed based upon the insight from the organic and inorganic fragments. The present study provides valuable information required for the design of novel MOFs with improved affinity for H₂ adsorption.     

Study on catalytic effect and mechanism of MOF (MOF = ZIF-8, ZIF-67, MOF-74) on hydrogen storage properties of magnesium

Using a deposition-reduction method, Mg/MOF nanocomposites were prepared as composites of Mg and metal-organic framework materials (MOFs = ZIF-8, ZIF-67 and MOF-74). The addition of MOFs can enhance the hydrogen storage properties of Mg. For example, within 5000 s, 0.6 wt%, 1.2 wt%, 2.7 wt%, 3.7 wt% of hydrogen were released from Mg, Mg/MOF-74, Mg/ZIF-8, Mg/ZIF-67, respectively. Activation energy values of 198.9 kJ mol⁻¹ H₂, 161.7 kJ mol⁻¹ H₂, 192.1 kJ mol⁻¹ H₂ were determined for the Mg/ZIF-8, Mg/ZIF-67, Mg/MOF-74 hydrides, which are 6 kJ mol⁻¹ H₂, 43.2 kJ mol⁻¹ H₂, and 12.8 kJ mol⁻¹ H₂ lower than that of Mg hydride, respectively. Moreover, the cyclic stability characterizing Mg hydride was significantly improved when adding ZIF-67. The hydrogen storage capacity of the Mg/ZIF-67 nanocomposite remained unchanged, even after 100 cycles of hydrogenation/dehydrogenation. This excellent cyclic stability may have resulted from the core-shell structure of the Mg/ZIF-67 nanocomposite.     

Equilibrium,kinetics and enthalpy of hydrogen adsorption in MOF-177

Metal–organic framework (MOF-177) was synthesized, characterized and evaluated for hydrogen adsorption as a potential adsorbent for hydrogen storage. The hydrogen adsorption equilibrium and kinetic data were measured in a volumetric unit at low pressure and in a magnetic suspension balance at hydrogen pressure up to 100 bar. The MOF-177 adsorbent was characterized with nitrogen adsorption for pore textural properties, scanning electron microscopy for morphology and particle size, and X-ray powder diffraction for phase structure. The MOF-177 synthesized in this work was found to have a uniform pore size distribution with median pore size of 12.7 Å, a higher specific surface area (Langmuir: 5994 m²/g; BET: 3275 m²/g), and a higher hydrogen adsorption capacity (11.0 wt.% excess adsorption, 19.67 wt.% absolute adsorption) than previously reported values on MOF-177. Freundlich equation fits well the hydrogen adsorption isotherms at low and high pressures. Diffusivity and isosteric heat of hydrogen adsorption were estimated from the hydrogen adsorption kinetics and equilibrium data measured in this work.     

F-doped CeO2 supported Co-based nanoparticles for enhanced photocatalytic H2 evolution from ammonia borane

Doping as a common mean to generate defects to boost the catalytic performance of metal oxide semiconductor-based materials has aroused great interest. However, doping usually requires high temperatures and is time consuming. Herein, we report a facile strategy for the preparation of F doped CeO₂ (F–CeO₂) with assistance of the electrostatic attraction between F⁻ and CeO₂ with oxygen vacancies at room temperature, then F–CeO₂ acts as superior support of metal Co nanoparticles (NPs) for efficient hydrolysis of NH₃BH₃ under light irradiation. The activity of Co/F–CeO₂ is significantly enhanced and Co/F–CeO₂-0.6 exhibited highest catalytic activity with TOF value 92.8 min⁻¹ which increases 47% compared with Co/CeO₂. Experimental and characterization results show the enhanced performance attributes to high efficiency photogenerated carrier separation and boosting adsorption capacity of H₂O and NH₃BH₃ over Co/F–CeO₂ due to F doped into CeO₂ crystallites. Furthermore, theory calculations further confirm that the band gap of F–CeO₂ becomes smaller and F–CeO₂ is more favorable the adsorption for H₂O and NH₃BH₃ than pure CeO₂. This work offers a facile and time efficiency strategy to realize controllable element doped in metal oxide under ambient, and gives deep insights into the structure–activity relationship of catalyst between defect engineering and photocatalytic performance.     

Efficient synthesis for large-scale production and characterization for hydrogen storage of ligand exchanged MOF-74/174/184-M (M = Mg2+, Ni2+)

A semitechnical route (optimized by BASF SE) to synthesize MOF-74/174-M (M = Mg²⁺, Ni²⁺) efficiently in ton-scale production is presented with the goal of mobile and stationary gas storage applications especially for hydrogen as future energy carrier. In addition, a new member of these series of materials, MOF-184-M (M = Mg²⁺, Ni²⁺) is introduced using ligand exchange strategy in order to produce a more porous analogue (possessing large aperture) without loss of crystallinity. This family comprising MOF-74/174/184 are characterized systematically for hydrogen adsorption properties by volumetric measurements with a Sieverts’ apparatus. Replacing the linker by a longer one results in an increase of the BET area from 984 to 3154 m²/g and an enhancement of the excess cryogenic (77 K) hydrogen storage capacity from 1.8 to 4.7 wt%. The heat of adsorption of linker exchanged MOF-174/184 (as a function of uptake) shows similar values to the parent MOF-74, indicating successful construction of expanded MOFs in large scale production. Finally, a usable capacity of these MOFs is investigated for mobile application, revealing that the increasing surface area without strong binding metal sites through longer linker exchange is one of important parameters for improving usable capacity.     

Ab initio and periodic DFT investigation of hydrogen storage on light metal-decorated MOF-5

The effect of light metal (M = Li, Be, Mg, and Al) decoration on the stability of metal organic framework MOF-5 and its hydrogen adsorption is investigated by ab initio and periodic density functional theory (DFT) calculations by employing models of the form BDC:M₂:nH₂ and MOF-5:M₂:nH₂, where BDC stands for the benzenedicarboxylate organic linker and MOF-5 represents the primitive unit cell. The suitability of the periodic DFT method employing the GGA-PBE functional is tested against MP2/6-311 + G* and MP2/cc-pVTZ molecular calculations. A correlation between the charge transfer and interaction energies is revealed. The metal-MOF-5 interactions are analyzed using the frontier molecular orbital approach. Difference charge density plots show that H₂ molecules get polarized due to the charge generated on the metal atom adsorbed over the BDC linker, resulting in electrostatic guest-host interactions.Our solid state results show that amongst the four metal atoms, Mg and Be decoration does not stabilize the MOF-5 to any significant extent. Li and Al decoration strengthened the H₂-MOF-5 interactions relative to the pure MOF-5 exhibited by the enhanced binding energies. The hydrogen binding energies for the Li- and Al-decorated MOF-5 were found to be sensible for allowing reversible hydrogen storage at ambient temperatures. A high hydrogen uptake of 4.3 wt.% and 3.9 wt.% is also predicted for the Li- and Al-decorated MOF-5, respectively.     

MOF-74-immobilized ternary RhNiP nanoparticles as highly efficient hydrous hydrazine dehydrogenation catalysts in alkaline solutions

For the first time, a series of highly efficient RhNiP@MOF-74 nanocomposite catalysts were synthesized by a one-step reduction process, subsequently characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Synergistic electronic effects between Rh, Ni, and P, along with electron transfer phenomena between RhNiP and MOF-74 resulted in outstanding catalytic activities towards the dehydrogenation of hydrous hydrazine in an alkaline solution (2 M NaOH) at 50 °C. The turnover frequency (TOF) value of Rh₄₇Ni₁₈P₃₅@MOF-74 reached 715.4 mol H₂·h⁻¹(mol metal)⁻¹ with 100% hydrogen selectivity, and there was no significant decrease even after five cycles.     

Li-Crown ether complex inclusion in MOF materials for enhanced H2 volumetric storage capacity at room temperature

The organometallic Li-Crown ether species, formed by the complexation of lithium cation with the hydrophobic 18Crown6 ether, has been included in three Metal-Organic-Frameworks (MOF) structures with different pore size: Cr-MIL-101, Fe-MIL100 and Ni-MOF-74. X-ray powder diffraction, thermogravimetric analysis, proton nuclear magnetic resonance, infrared spectroscopy and inductively coupled plasma atomic emission spectroscopy measurements have proved the successful incorporation of the organometallic units to the three MOFs without altering their crystalline structure. Hydrogen adsorption properties of the post-synthesis modified materials have been evaluated in a wide temperature (77–298 K) and pressure (1–170 bar) range conditions. The post-synthetic modification method used based on the MOF impregnation with a Li-Crown ether complex solution produced a partial pore blocking effect on the microporous Ni-MOF-74, reducing its hydrogen adsorption capacity. However, the inclusion of the crown-ether and particularly the Li-Crown ether complex resulted in an increase of the volumetric hydrogen adsorption capacity at room temperature for Cr-MIL101 and Fe-MIL-100, due to the pore volume reduction, higher confinement of H₂ molecules in the cavities and the formation of new specific binding sites for H₂ molecules. The inclusion of Li-Crown ether complex also enhances the H₂ interaction with the mesoporous MOF structures, attributed to the additional electrostatic interactions produced by the presence of Li⁺ ions complexed to the crown ether molecules. Further work following this strategy to improve hydrogen adsorption capacity of mesoporous MOFs at room temperature should be extended to other MOF materials, checking its influence on their capacity for gas separation purposes.     

Enhanced hydrogen storage capacity of Pt-loaded CNT@MOF-5 hybrid composites

We report on an easy synthesis method for the preparation of a hybrid composite of Pt-loaded MWCNTs@MOF-5 [Zn₄O(benzene-1,4-dicarboxylate)₃] that greatly enhanced hydrogen storage capacity at room temperature. To prepare the composite, we first prepared Pt-loaded MWCNTs, which were then incorporated in-situ into the MOF-5 crystals. The obtained composite was characterized by various techniques such as powder X-ray diffractometry, optical microscopy, porosimetry by nitrogen adsorption, and hydrogen adsorption. The analyses confirmed that the product has a highly crystalline structure with a Langmuir specific surface area of over 2000 m²/g. The hybrid composite was shown to have a hydrogen storage capacity of 1.25 wt% at room temperature and 100 bar, and 1.89 wt% at cryogenic temperature and 1 bar. These H₂ storage capacities represent significant increases over those of virgin MOF-5s and Pt-loaded MWCNTs.     

Enhancement of hydrogen adsorption by alkali-metal cation doping of metal-organic framework-5

Over the past decade, metal-organic frameworks (MOFs) have been extensively studied as a novel approach to store hydrogen. The large surface area and volume of micropores that are intrinsic to MOFs make them ideal for gas adsorption. In addition, we chemically reduced MOF-5 by doping it with alkali metals (Li, Na, and K). We found that the H₂ uptake capacity of MOF-5 materials doped with Li, Na, and K exceeded that of a neutral framework by 24%, 68%, and 70%, respectively. Notably, at the same levels of doping, the Li⁺-doped framework exhibited the strongest H₂ binding, and the binding strength decreased sequentially in the order Li⁺ > Na⁺ > K⁺.     

Enhanced photoelectrochemical hydrogenation of green-house gas CO2 to high-order solar fuel on coordinatively unsaturated metal-N sites containing carbonized Zn/Co ZIFs

Porous carbon-based catalysts facilitate CO₂ photoelectrochemical reduction reaction (CO2PRR) through the high charge transfer ability and CO₂ adsorption ability. However, the design of catalysts with high selectivity towards high-order solar fuels (such as ethanol and propanol) remains challenging. Herein, catalysts of carbonized Zn/Co Zeolitic Imidazolat Frameworks with various pyrolysis hours (xh-C-Zn/Co ZIFs) were synthesized and accessed for high selective CO2PRR for the first time. XRD and TEM analyses show that the C containing functional groups in pristine Zn/Co ZIF are carbonized and turned into amorphous porous carbon, while many Co and ZnO nanoparticles are formed during the pyrolysis process. Electrochemical characterizations of the catalysts prove that increasing pyrolysis time of Zn/Co ZIF from 1 h to 3 h, resulting in a decreased light current density from 3.3 mA/cm² to 2.3 mA/cm², which is much higher than that of Zn/Co ZIF (1.9 mA/cm²). Meanwhile, increasing pyrolysis time of Zn/Co ZIF from 1 h to 3 h results in decreased BET surface area and CO₂ adsorption ability. XPS spectra suggest a decreased content of metal-nitrogen bonds in C–Zn/Co ZIF, which leads to the formation of coordinatively unsaturated metal-nitrogen sites. Density functional theory (DFT) calculations reveal that the coordinatively unsaturated CoN₃V sites in C–Zn/Co ZIF had the highest catalytic activity towards high-order organics. The total carbon atom conversion rate reaches 5459 nmol/h·cm² when 1h-C-Zn/Co ZIF is employed as catalyst in the CO2PRR system and the selectivity towards high-order solar fuel reaches 84%.     

Construction of new alternative transmission sites by incorporating structure-defect metal-organic framework into sulfonated poly(arylene ether ketone sulfone)s

Metal-organic frameworks are new kinds of porous crystalline materials. The Zr-based metal-organic framework (MOF-801) is consists of [Zr₆(u₃-O)₄(u₃-OH)₄]¹²⁺ clusters and fumaric acid connectors. MOF-801 has excellent mechanical properties, high chemical stability and high water absorption capacity. There are a large number of hydrophilic functional groups inside MOF-801, which is effective to promote interfacial compatibility between MOF-801 and polymer matrixes. In this work, the MOF-801 with structural defects was synthesized through the solvothermal method by adding excess formic acids as the regulator. These structural defects could confer MOF-801 high surface area (2476.34 m² g^?1) and promote the water absorption capacity. Moreover, structural defects could also expose more open metal sites of MOF-801, thereby increasing the Lewis acidity of MOF-801. Then, the hybrid membranes were synthesized by combining the MOF-801 with structural defects and C-SPAEKS. Dense hydrogen-bond networks formed between the MOF-801 and C-SPAEKS further promote enhance proton conductivity. At the condition of 90 °C and 100% relative humidity, the highest proton conductivity of hybrid membranes reached 0.100 S cm^?1, which is similar to that of Nafion 117. Meanwhile, these hybrid membranes showed outstanding chemical and thermal stabilities. These results indicate that these hybrid membranes have potential as proton exchange membranes.     

Multiscale study of the structure and hydrogen storage capacity of an aluminum metal-organic framework

First-principles calculations based on density functional theory and Grand Canonical Monte Carlo (GCMC) simulations are carried out to study the structure of a new Aluminum Metal-Organic Framework, MOF-519, and the possibility of storing molecular hydrogen therein. The optimized structure of the inorganic secondary building unit (SBU) of MOF-519 formed by eight octahedrally coordinated aluminum atoms is presented. The different storage sites of H₂ inside the SBU and the BTB ligand are explored. Our results reveal that the SBU exhibits two different favorable physisorption sites with adsorption energies of ?12.2 kJ/mol and ?1.2 kJ/mol per hydrogen molecule. We have also shown that each phenyl group of BTB has three stable H₂ adsorption sites with adsorption energies between ?6.7 kJ/mol and ?11.37 kJ/mol. Using GCMC simulations; we calculated the molecular hydrogen (H₂) gravimetric and volumetric uptake for the SBU and MOF-519. At 77 K and 100 bar pressure, the hydrogen uptake capacity of SBU is considerably enhanced, reaching 16 wt.%. MOF-519 has a high gravimetric uptake, 10 wt.% at 77 K and 4.9 wt.% at 233 K. It has also a high volumetric capacity of 65 g/L at 77 K and 20.3 g/L at 233 K, indicating the potential of this MOF for hydrogen storage applications.     

Effect of calcium ions on biohydrogen production performance in a fluidized bed bioreactor with activated carbon-immobilized cells

Hydrogen (H₂) has become a promising energy source because it is clean and has high-energy potential. The aim of this research was to enhance the H₂ production efficiency under anaerobic condition by addition of calcium ions (Ca²⁺) in a fluidized bed reactor (FBR) with immobilized cells. Ca²⁺ ions were added either in the form of Ca(OH)₂ or CaCl₂. Immobilized cells were prepared by physical adsorption with activated carbon (AC). The experiments were carried out in a FBR system. The H₂ production performance of the FBR fed with sucrose-based synthetic medium, was evaluated under various influent Ca²⁺ concentrations [Ca²⁺] (50, 100 and 200 ppm) and hydraulic retention times (HRTs) (8, 6, 4 and 2 h). The peak value of 1.22 L/h-L was obtained at [Ca²⁺] 100 ppm, irrespective of the form of Ca²⁺ ion added, and at the HRT of 2 h. Although the results were similar for different forms of Ca²⁺ ions, the presence of Ca²⁺ ions enhanced the H₂ producing bioprocess by 12–18%.     

Be2+ and Mg2+-decorated sulflower: Potential systems for molecular hydrogen storage

The hydrogen binding efficiency of multiple metal-ion (Be²⁺, Mg²⁺)-decorated “First Generation” Sulflower (C₁₆S₈) systems has been investigated for the first time using density functional ω-B97XD method and 6311++G(d,p) basis set. Our calculations show that the central ring of the aforesaid system can be decorated by a single di-positive metal ion, followed by favorable decoration of at most one pair of metal ions (di-positive each) on the peripheral five-membered rings, both on same and opposite faces with certain preferences. All of the metal ion-decorated complexes are capable of efficient hydrogen binding. Be²⁺ and Mg²⁺-decked single ion complexes effectively bind six and four H₂ molecules respectively. Moreover, each of the double ion-decorated systems can adsorb ten H₂ molecules irrespective of the facial orientation of the metal ions. The average interaction energy (ΔE) between sulflower and metal ions (single and double ions) as well as the average binding energy (ΔBE) per molecular hydrogen of the concerned metal-ion-decorated complexes is found to be much higher for Be²⁺-decked systems. The nature of interaction between hydrogen molecules and metal ions is explicated by the topological analysis (AIM Analysis) and NBO formalisms. In case of Be²⁺-decked systems, the amount of charge transfer from H₂ bonding orbital to metal anti-bonding orbital is much higher than analogous Mg²⁺-decorated systems. The Natural Population Analysis (NPA) evaluates the charge variation on the acceptor metal ions due to hydrogen adsorption. In short, our theoretical study gives a comprehensive account of the relationship between the metal ion-decorated sulflower systems and hydrogen molecules, which will further motivate researchers in the field of efficient hydrogen storage materials.     

First principle study on transition metal ammine borohydrides with amphoteric hydrogen for hydrogen storage applications

Usually the ions of a particular element in solids either in positive or in negative oxidation states, which are influenced by their chemical circumstances. Thus, it is quiet interesting for an atom having both positive and negative oxidation states within the same structural framework in a particular compound. Our structural and chemical bonding analyses show that the hydrogen ions in the transition metal ammine borohydrides (TMABHs) with the chemical formula M(BH₄)₂(NH₃)₂ (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) have both + and − oxidation states. Moreover, our detailed analyses show that the hydrogen present in these compounds have amphoteric behaviour with hydrogen closer to boron is in negative oxidation state and that closer to nitrogen is in the positive oxidation state. The spin-polarised van der Waals interaction included calculation show that all these materials except M = Zn are having finite magnetic moment at the transitions metal site with the anti−ferromagnetic ordering as ground state. The localised magnetic moment similar to those present in molecular magnet with large band gap value indicating that these transparent magnets may find application in novel devices. Our nudged elastic band calculation show that the migration barrier for ammonia diffusion in these materials are more than 1 eV and hence these compounds may be used for energy storage applications since they have high weight percentage of hydrogen. The confirmation of the presence of amphoteric behaviour of hydrogen in TMABHs has implication in designing volume efficient hydrides for hydrogen storage applications.