Catalytic activity of Co–Ag nanoalloys to dissociate molecular hydrogen. New insights on the chemical environment

Adsorption of molecular hydrogen on the surface of catalytic metal nanoparticles and its dissociation in atomic hydrogen are processes of interest in many chemical technologies. As in other chemical reactions, alloying can improve the efficiency of the catalysts. By focusing on Co₆, Co₅Ag, Co₃Ag₃ and CoAg₅, we explore the effect of changing the relative concentration of the two components in small Co_mAg_n clusters, a peculiar nanoalloy because Co and Ag do not form bulk solid alloys. Molecular hydrogen adsorbs preferentially on the Co atoms, and the binding is mainly due to the electrical polarization of the charges of adsorbate and host. The preference for Co sites and the trend in the strength of the H₂-cluster binding are explained by the combination of two effects characterizing the host environment. One of these is geometric, arising from the degree of exposure of the host atom: the lower the atomic coordination of the host atom, the stronger its bonding with H₂. The second effect, newly identified, reveals the importance of the chemical nature of the host atom environment: host Co atoms having both Co and Ag neighbors maintain their capacity to bind hydrogen more intact than those with only Co neighbors. The alloy nanoclusters catalyze the dissociation of adsorbed H₂ by building up quite small activation barriers. After dissociation, the H atoms occupy bridge positions between Co atoms (between Co and Ag in CoAg₅). H₂ adsorption and dissociation may trigger structural transformations of the cluster. The work shows that the adsorption and dissociation properties of H₂ can be tuned by varying the relative composition of the two atomic species in the nanoalloy.     

Doping the transition metal atom Fe,Co, Ni into C48B12 fullerene for enhancing H2 capture: A theoretical study

The feasibility of transition metal coated fullerene cages M₁₂C₄₈B₁₂(M = Fe, Co, and Ni) for hydrogen storage is investigated by the pseudopotential density functional theory. Fe₁₂C₄₈B₁₂(Co₁₂C₄₈B₁₂ and Ni₁₂C₄₈B₁₂) adsorbs 60(48 and 48) H₂ with moderate average adsorption energy of 0.50(0.45 and 0.32) eV/H₂. The gravimetric hydrogen density of Fe₁₂C₄₈B₁₂(Co₁₂C₄₈B₁₂ and Ni₁₂C₄₈B₁₂) can reach 8.7(6.8 and 6.8) wt%. The Dewar–Kubas interaction dominates the adsorption of H₂ on the outer surface of Fe₁₂C₄₈B₁₂(Co₁₂C₄₈B₁₂ and Ni₁₂C₄₈B₁₂). Therefore, the stable M₁₂C₄₈B₁₂(M = Fe, Co, and Ni) cages can be applied as candidates for hydrogen storage under near-ambient conditions.     

Revealing the interfacial phenomenon of metal-hydride formation and spillover effect on C48H16 sheet by platinum metal catalyst (Pt (n=1-4)) for hydrogen storage enhancement

Hydrogen is a worldwide green energy carrier, however due its low storage capacity, it has yet to be widely used as an energy carrier. Therefore, the quantum chemical method is being employed in this investigation for better understand the hydrogen storage behaviour on Pt _(n = 1-4) cluster decorated C₄₈H₁₆ sheet. The Pt_(n = 1-4) clusters are strongly bonded on the surface of C₄₈H₁₆ sheet with binding energies of ?3.06, ?4.56, ?3.37, and ?4.03 eV respectively, while the charge transfer from Pt_(n = 1-4) to C₄₈H₁₆ leaves an empty orbital in Pt atom, which will be crucial for H₂ adsorption. Initially, the molecular hydrogen is adsorbed on Pt_(n = 1-4) decorated C₄₈H₁₆ sheet through the Kubas interaction with adsorption energies of ?0.85, ?0.66, ?0.72, and ?0.57 eV respectively, while H–H bond is elongated due to the transfer of electron from σ (HH) orbital to unfilled d orbital of the Pt atom, resulting in a Kubas metal-dihydrogen complexes. Furthermore, the dissociative hydrogen atoms adsorbed on Pt_(n = 1-4) decorated C₄₈H₁₆ sheet have adsorption energies of ?1.14 eV, ?1.02 eV, ?0.95 eV, and ?1.08 eV, which are greater than the molecular hydrogen adsorption on Pt_(n = 1-4) cluster supported C₄₈H₁₆ sheet with lower activation energy of 0.007, 0.109, 0.046, and 0.081 eV respectively. To enhance the dissociative hydrogen adsorption energy, positive and negative external electric fields are applied in the charge transfer direction. Increasing the positive electric field makes H–H bond elongation and good adsorption, whereas increasing the negative electric field results H–H bond contraction and poor adsorption. Thus, by applying a sufficient electric field, the H₂ adsorption and desorption processes are can be easily tailored.     

Enhanced activity of Co catalysts supported on tungsten carbide-activated carbon for CO2 reforming of CH4 to produce syngas

Carbon materials are widely used as catalysts or supports due to their excellent properties. In this paper, the tungsten carbide-activated carbon (WC-AC) composite support was successfully prepared by in-situ carburizing on AC matrix, which is characterized by the covalent anchoring of WC on the AC support. The active metal Co was supported on WC-AC for dry reforming of methane (DRM). Samples were analyzed by N₂ physisorption measurements, XRD, XPS, H₂-TPR, H₂-TPD, CH₄&CO₂-TPSR, TG-DTG. The WC-AC stabilizes the disturbance of C in AC, alleviates the gasification effect of CO₂ and increases the active sites for CH₄ cracking. Moreover, WC provides a resistance-less bridge suitable for the Co³⁺ → Co²⁺, resulting in a high Co²⁺/Co³⁺ ratio on the catalyst surface. This enhances the interaction between the Co species and the WC-AC, thereby enhancing the CH₄ activation. In the process of WC-AC promoting Co³⁺→Co²⁺, the catalyst surface is accompanied by the generation of oxygen vacancies. This can enhance the dissociative adsorption of CO₂ on surface of the WC-cobalt oxide, and at the same time increase the relative proportion of adsorbed oxygen on the catalyst surface, thereby effectively inhibiting the formation of coke. However, the small amount of graphitic carbon generated due to the strong coupling of WC and Co is the main reason for deactivation of Co/WC-AC.     

The effect of charge on the dihydrogen storage capacity of Sc2–C6H6

The effect of charge on the dihydrogen storage capacity of Sc₂–C₆H₆ has been investigated at B3LYP-D3/6-311G(d,p) level. The neutral system Sc₂–C₆H₆ can store 8H₂ with gravimetric density of 8.76 wt %, and one H₂ dissociates and bonds atomically on the scandium atom. The adsorption of 8H₂ on Sc₂–C₆H₆ is energetically favorable below 155 K. The atom-centered density matrix propagation (ADMP) molecular dynamics simulations show that Sc₂–C₆H₆ can adsorb 3H₂ within 1000 fs at 300K. Compared with Sc₂–C₆H₆, the charged systems can adsorb more hydrogen molecules with higher gravimetric density, and all the H₂ are adsorbed in the molecular form. The gravimetric densities of Sc₂–C₆H₆⁺ and Sc₂–C₆H₆²⁺ are 9.75 and 10.71 wt%. Moreover, the maximum adsorption of charged systems are favorable in wider temperature range. Most importantly, the ADMP-MD simulations indicate that Sc₂–C₆H₆²⁺ can adsorb 6 hydrogen molecules within 1000 fs at 300K. It can be found that the gravimetric density (6.72 wt%) of Sc₂–C₆H₆²⁺ still exceeds the target of US Department of Energy (DOE) under ambient conditions.     

Theoretical studies on hydrogen adsorption properties of lithium decorated diborene (B2H4Li2) and diboryne (B2H2Li2)

Using ab initio based quantum chemical calculations, we have studied the structure, stability and hydrogen adsorption properties of different boron hydrides decorated with lithium, examples of the corresponding anions being dihydrodiborate dianion, B₂H₂²⁻ and tetrahydrodiborate dianion, B₂H₄²⁻ which can be considered to be analogues and isoelectronic to acetylene (C₂H₂) and ethelene (C₂H₄) respectively. It is shown that there exists a B-B double bond in B₂H₄Li₂ and a B-B triple bond in B₂H₂Li₂. In both the complexes, the lithium sites are found to be cationic in nature and the calculated lithium ion binding energies are found to be very high. The cationic sites in these complexes are found to interact with molecular hydrogen through ion-quadrupole and ion-induced dipole interactions. In both the complexes, each lithium site is found to bind a maximum of three hydrogen molecules which corresponds to a gravimetric density of ∼23 wt% in B₂H₄Li₂ and ∼24 wt% in B₂H₂Li₂. We have also studied the hydrogen adsorption in a model one-dimensional nanowire with C₆H₄B₂Li₂ as the repeating unit and found that it can adsorb hydrogen to the extent 9.68 wt% and the adsorption energy is found to be −2.34 kcal/mol per molecular hydrogen.     

Evaluation of the hydrogen adsorption onto Li and Li+ decorated circumtrindene (C36H12): A theoretical study

Circumtrindene as a π-bowl shaped carbon structure decorated by Li and Li⁺ and examined for H₂ adsorption using M06-2X/6-311++G(d,p)//B3LYP/GEN level of theory. All polygons, bonds and various carbon types, in concave and convex sides, were examined to find the best location for Li and Li⁺. ZPE and BSSE-corrected interaction energy values were calculated for connection of Li or Li⁺ to circumtrindene and for connection of H₂ to LiC₃₆H₁₂ or Li⁺-C₃₆H₁₂. Better understanding of the adsorption properties were achieved by DOS, PDOS, OPDOS diagrams and NBO analysis. Results showed that in LiC₃₆H₁₂ and Li⁺-C₃₆H₁₂ complexes, the concave side has more binding energy than the convex ones and Li⁺-C₃₆H₁₂ has more binding energy than LiC₃₆H₁₂. Also, for LiC₃₆H₁₂, when Li was in center polygon and concave side and for Li⁺-C₃₆H₁₂, when Li⁺ was in 6-2 polygon and convex side, the highest interaction energy were obtained. For H₂ adsorption, the complexes contain Li and Li⁺ in center polygon and concave face have the highest binding energy, equal to 15.72 and 16.29 kcal mol^?1, respectively. Binding energy values indicated that adsorption of Li or Li⁺ onto C₃₆H₁₂ and adsorption of H₂ onto LiC₃₆H₁₂ or Li⁺-C₃₆H₁₂ in all positions are chemisorptions, but the connections are not so strong for H₂ molecules.     

Selective decoration of nitrogenated holey graphene (C2N) with titanium clusters for enhanced hydrogen storage application

For an envisioned hydrogen (H₂) economy, the design of new multifunctional two-dimensional (2D) materials have been a subject of intense research for the last several decades. Here, we report the thriving H₂ storage capacity of 2D nitrogenated holey graphene (C₂N), functionalized with Ti_n (n = 1–5) clusters. By using spin polarized density functional theory (DFT) calculations implemented with the van der Waals corrections, the most favourable adsorption site for the Ti_n clusters on C₂N has been revealed. With the monomer Ti, the functionalization was evenly covered on C₂N having 5% doping concentration (C₂N–Ti). For C₂N–Ti sheet, Ti binds to C₂N with a strong binding energy of ~6 eV per Ti which is robust enough to hinder any Ti–Ti clustering. Bader charge analysis reveals that the Ti_n clusters donate significant charges to C₂N sheet and become cationic to polarize the H₂ molecules, thus act as efficient anchoring agents to adhere multiple H₂ molecules. Each Ti in C₂N–Ti could adsorb a maximum of 10H₂ molecules, with the adsorption energies in the range of ?0.2 to ?0.4 eV per H₂ molecule, resulting into a high H₂ storage capacity of 6.8 wt%, which is promising for practical H₂ storage applications at room temperature. Furthermore, Ti_m (m = 2, 3, 4, 5) clusters have been selectively decorated over C₂N. However, with Ti_m functionalization H₂ storage capacities fall short of the desirable range due to large molecular weights of the systems. In addition, the H₂ desorption mechanism at different conditions of pressure and temperature were also studied by means of thermodynamic analysis that further reinforce the potential of C₂N–Ti as an efficient H₂ storage material.     

Layered lithium cobalt nitrides: A new class of lithium intercalation compounds

Lithium cobalt nitrides Li_3−2xCo_xN (0.1 ≤ x ≤ 0.44) have been prepared and investigated as negative electrode in the 1/0.02 V potential window. The evolution of the unit cell parameters and unit cell volume with the Co content show a solid solution behaviour. Whatever the Co content, all these nitrides are electroactive with a single step around 0.6 V/0.7 V for the discharge and charge processes, respectively. The electrochemical behaviour observed is typical of a Li intercalation compound and involves the Co²⁺/Co⁺ redox couple in the interlayer plane combined with the reversible accommodation of Li⁺ ions in the cation vacancies located in Li₂N⁻ layers. XRD experiments performed after discharge, charge and cycling tests clearly indicate the hexagonal layered structure of the host lattice is maintained. This intercalation process explains the excellent capacity retention found after 50 cycles. A specific capacity of 180 mAh g⁻¹ at C/20 and 130 mAh g⁻¹ at C/5 rate (100 mA cm⁻²) is achieved for Li_2.23Co_0.39N. ac impedance measurements have allowed to characterize the kinetics of the reaction.     

Role of extraframework metal sites for hydrogen adsorption into the pores of a zeolite: FT-IR study

In order to compare the adsorptive properties of nanoporous zeolites containing extraframework cations of different nature, we have studied the interaction of H₂ with Na-A, Ca-A, and Co,Na-A zeolites. Low temperature Fourier transform infrared (FT-IR) spectroscopy was used for the investigation, as this technique is highly sensitive and responsive to the nature of the gas/surface interaction and can in addition allow for the estimation of the adsorption enthalpy. In all cases the spectra of adsorbed H₂ have complex structure due to ortho/para splitting as well as to surface structural disorder. Na⁺ and divalent Ca²⁺ were found to induce almost similar perturbation on H₂ molecule, resulting in the shift of the H-H vibrational frequency of −86 cm⁻¹ and −76 cm⁻¹ respectively (as compared to the Raman frequency of gaseous H₂). The enthalpy of adsorption, estimated by the Variable Temperature Infrared (VTIR) method, is −13 ± 1 kJ mol⁻¹ for the strongest adsorptive sites in Na-A and Ca-A samples. In the case of Co,Na-A the shift of the H-H frequency due to the formation of H₂?Co²⁺ complexes is larger (ca. −180 cm⁻¹) suggesting that the interaction can involve some, although small, chemical contribution.     

Cobalt-based coordination polymer as high activity electrocatalyst for oxygen reduction reaction: Catalysis by novel active site CoO4N2

[{Co₃(μ₃-OH)(BTB)₂(BPE)₂}{Co_0.5N(C₅H₅)}] (Co-CP) as a coordination polymer for catalyzing oxygen reduction reaction (ORR) has recently been reported to exhibit high ORR performance because of its novel structural characteristics. Nevertheless, the detailed mechanism remains far from enough. Herein, first-principles study of the ORR process of Co(C₆H₅CO₂)₂(C₅H₅N)₂ is carried out, which is the constructed model of monomeric unit for this compound. Most interestingly, the calculated results uncover that in the second proton transfer step, the active site contributes to the reaction is not only the Co atom, but also the O and N atoms which are directly bonded to the Co atom that construct a novel active site CoO₄N₂. Further analysis of the electronic structure demonstrates that the Co, O, and N atoms in the CoO₄N₂ local structure have participated the electron transfer during the entire ORR process. By analyzing the relative energy changes of whole reaction, it can find that the favorable ORR pathway on the Co(C₆H₅CO₂)₂(C₅H₅N)₂ is the 4e⁻ pathway, and the overpotential of ORR on Co(C₆H₅CO₂)₂(C₅H₅N)₂ is calculated as 0.43 V, which is consistent with experimental observation and lower than that on the Pt(111). Furthermore, the results of first-principles molecular dynamics simulations and density of states (DOS) show that Co(C₆H₅CO₂)₂(C₅H₅N)₂ presents good stability. And it also possesses high anti-poisoning ability to some impurity gases such as CO, NO, and NH₃.     

Pd loading,Mn+ (n=1, 2, 3) metal ions doped TiO2 nanosheets for enhanced photocatalytic H2 production and reaction mechanism

Pd nanoparticles (NPs) loading, main group metal ions doped TiO₂ nanosheets were prepared by a hydrothermal method, followed by photo-deposition of Pd. The samples were characterized, and their photocatalytic hydrogen production activities were tested in a methanol aqueous solution. The effects of cationic charge, radius and concentration of the doping ions (Na⁺, K⁺, Mg²⁺, Al³⁺) on the photocatalytic activities were investigated systematically. The photocatalytic reaction mechanism was discussed by considering the three aspects: specific surface area, light absorption and charge transfer/separation. The results show that the cation dopings significantly increased the photocatalytic activities of the TiO₂ nanosheets, which may be attributed to the enhanced UV-vis light absorption and accelerated charge transfer/separation of the catalysts. Particularly, the Pd/0.2%K⁺-TiO₂ possesses the highest photocatalytic H₂ production activity (76.6 μmol h^?1), which is more than twofold higher than that of the undoped Pd/TiO₂. The apparent quantum efficiency of hydrogen evolution system reaches 3.0% at 365 nm. The high activity of the Pd/K⁺-TiO₂ may be attributed to the lower electronegativity of K⁺, caused by the lower cationic charge or the larger cationic radius, compared to Na⁺, Mg²⁺ and Al³⁺. The doping metal cations with higher electronegativity may compete electrons with H⁺, which eventually partly depressed the reduction of H⁺ to H₂.     

Lithium clusters on graphene surface and their ability to adsorb hydrogen molecules

This research describes the theoretical study of the adsorption of lithium clusters on graphene and the ability to capture hydrogen molecules. The results of the studied structures showed that the [Li₁C₅₄H₁₈]⁺ system is capable of accepting three hydrogen molecules showing adsorption energies of 0.12 eV. On the other hand, it is important to note that in [Li_nC₅₄H₁₈] n = 2–6 systems, the lithium atoms that do not interact with the graphene surface, they can adsorb up to four hydrogen molecules. The [Li₆C₅₄H₁₈]4H₂ system presented a higher adsorption energy value of 0.31 eV. Finally, the Li–H₂ interactions were characterized by a NBO analysis, which showed that hydrogen atoms are the donors and lithium atoms are the acceptors.     

Transition metal atom Fe,Co, Ni decorated B38 fullerene: Potential material for hydrogen storage

The hydrogen storage capacity of M-decorated (M = Fe, Co, Ni) B₃₈ fullerene is investigated using first-principles calculations based on density functional theory. The Fe, Co, Ni atoms are strongly bound on hexagonal holes of B₃₈ fullerene without clustering. Fe₄B₃₈ (Co₄B₃₈ and Ni₄B₃₈) adsorbs 24H₂ with moderate average adsorption energy of 0.175 (0.184 and 0.202) eV/H₂. Based on density functional theory, the gravimetric density of Fe₄B₃₈ (Co₄B₃₈ and Ni₄B₃₈) could potentially reach 7.34 (7.21 and 7.22) wt%, respectively. Therefore, we infer that M-decorated (M = Fe, Co, Ni) B₃₈ fullerene could be a candidate for further investigation as an alternative material for hydrogen storage.     

Hydrogen storage capacity of alkali and alkaline earth metal ions doped carbon based materials: A DFT study

The hydrogen storage (H-storage) capacity of alkali (Li⁺, Na⁺ and K⁺) and alkaline earth metal ion (Mg²⁺ and Ca²⁺) doped cubane, cyclohexane and adamantane has been investigated using Density Functional Theory (DFT) based M05-2X functional employing 6-31+G∗∗ basis set. The adsorption of number of H₂ molecules on the metal ion doped complexes depends on ionic radii and charge of the metal ions. Among the 15 complexes investigated in this study, Mg²⁺ ion doped cubane, cyclohexane and adamantane complexes have higher H-storage capacity when compared to other complexes. The calculated binding energy (BE) of 5H₂@Cub-Mg²⁺ complex is 46.85 kcal/mol with binding energy per H₂ molecule (BE/nH₂) of 9.37 kcal/mol. The corresponding gravimetric density of the complexes is 7.3 wt%. In the case of 4H₂@Cyc-Mg²⁺ complex, the BE is 32.19 kcal/mol (BE/nH₂ is 8.05 kcal/mol with 6.9 wt% in gravimetric density). The Adm-Mg²⁺ complexes adsorb 4H₂ molecules with BE of 33.33 kcal/mol, the BE of per H₂ molecule is 8.33 kcal/mol. The corresponding gravimetric density of the complex is around 4.8 wt%, respectively. A new linker modified MOP-9 has been constructed based on the results and their H-storage capacity has also estimated.     

Hydrogen storage on cation-decorated biphenylene carbon and nitrogenated holey graphene

Hydrogen storage on cation-decorated biphenylene carbon (BPC) and nitrogenated holey graphene (C₂N) layered materials are addressed by dispersion-corrected density functional theory calculations. Maximum storage capacity and adsorption energy of a gas-phase H₂ monolayer adsorbed on both sides of (Li⁺, Na⁺, Mg²⁺, Ca²⁺)-doped layers are investigated. We find that cations distribute homogeneously on BPC and C₂N with a maximum densities of 1.9 and 1.7 ion/nm², respectively. The H₂ adsorption on cation-decorated BPC shows binding energies that vary from ?0.14 to ?0.26 eV/H₂, depending on whether the cation is single or double charged, where the storage capacity are calculated to be around 10 wt%. Whereas, for cation-doped C₂N, the H₂ binding energies vary from ?0.11 to ?0.31 eV/H₂, with storage capacity between 7.3 and 8.8 wt%. Our results suggest that cation-doped C₂N is the most stable material, providing both reversibility and high capacity for hydrogen storage at operational conditions.     

Functionalized tetrahedral silsesquioxane cages for hydrogen storage

The hydrogen storage capacity of functionalized Tetrahedral Silsesquioxane (H₄Si₄O₆) cages is obtained using density functional theory (M062X) and second order Møller-Plesset (MP2) method with 6-311++G7 basis set. We labelled Tetrahedral Silsesquioxane (H₄Si₄O₆) as ‘TS’. We replaced four hydrogen in TS one by one with C₂HBe or C₂HTi group and labelled as TSR₁M_1, TSR₂M₂ TSR₃M₃ and TSR₄M₄ where RM can be either C₂HBe or C₂HTi. In TSRM when one hydrogen in a cage is replaced by C₂HBe or C₂HTi 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 TSR_mM_m (m = 1, 2, 3 and 4) has increased extensively when all the hydrogen in cage are replaced either C₂HBe or C₂HTi. TSR₄M₄ with RM = C₂HTi 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.     

In situ observation of H2 dissociation on the ZnO (0001) surface under high pressure of hydrogen using ambient-pressure XPS

The interaction of H₂ molecules with a ZnO (0001) single crystal surface has been studied over a wide pressure (10^?6–0.25 Torr) and temperature (300–600 K) range using ambient pressure X-ray photoelectron spectroscopy (AP-XPS). ZnO is well-known for interstitial hydrogen and hydrogen atoms in ZnO are believed to be incorporated by the dissociative adsorption of H₂ molecules in the atmosphere and their subsequent diffusion into the bulk. The dissociative adsorption of H₂ has been investigated at elevated pressures because H₂ molecules are not dissociated on the ZnO single crystal surface under ultrahigh vacuum (UHV) conditions. When the pressure is increased to several mTorr, the dissociative adsorption of H₂ takes place to form OH bonds on the surface. At 0.25 Torr, the ZnO surface is saturated with H atoms and the coverage is estimated to be 1.1 × 10¹⁵ atoms/cm² at 300 K. At higher surface temperatures, the equilibrium between the dissociative adsorption of gas-phase H₂ molecules and the associative desorption of surface H atoms is established. While maintaining the equilibrium, the surface has been monitored successfully in situ by utilizing AP-XPS.     

A theoretical study on cage-like clusters (C12Ti6 and C12Ti62+) for dihydrogen storage

This work reports the dihydrogen adsorption and storage capacity of cage-like clusters (C₁₂Ti₆ and C₁₂Ti₆²⁺) using density functional theory calculations. The neutral system C₁₂Ti₆ can adsorb 15 hydrogen molecules, however, some hydrogen molecules will dissociate and bond atomically on titanium atoms. The strong binding energy will cause high operating temperature to desorb hydrogen during the application process. Fortunately, the cationic system C₁₂Ti₆²⁺ can adsorb up to 16H₂ all in molecular form. Moreover, the predicted maximal hydrogen storage density is 6.96 wt% and the average adsorption energies of C₁₂Ti₆²⁺ (nH₂) (n = 1–16) are in the desirable range of reversible hydrogen storage at the 6-311G(d,p)-B3LYP and M06-2X levels. The interaction of C₁₂Ti₆²⁺ with hydrogen molecules is considered by means of the bond critical points (bcp) in the quantum theory of atoms in molecules (QTAIM). With respect to Gibbs free energy corrected H₂ adsorption energy, C₁₂Ti₆²⁺ adsorbs 16H₂ molecules should be at low temperature (190 K). These predictions show that cationic C₁₂Ti₆²⁺ is more suitable as a material for adsorbing dihydrogen.