Papers by Keyword: Hydrogen Adsorption

Abstract: As lithium-ion batteries have their difficulties, the demand to improve beyond-lithium batteries goes beyond the issues of sustainability and safety. With the pressure for renewable energy resources and the enchantingly digitalized current lifestyle, the need for batteries will augment. Therefore, in this article, sodium and potassium have been evaluated as the promising alternative alkali metals in the ion batteries. A comprehensive investigation on hydrogen grabbing by Li₂ [SiO–SnO], Na₂ [SiO–SnO] or K₂ [SiO–SnO] was carried out using density functional theory (DFT) computations at the Coulomb-attenuating method–Becke, 3-parameter, Lee-Yang-Parr with Dispersion–corrected (CAM–B3LYP–D3/6–311+G (d,p)) level of theory. The hypothesis of the hydrogen adsorption phenomenon was confirmed by density distributions of charge density differences (CDD), total density of states (TDOS), overlap Population density of state (OPDOS) and localized orbital locator (LOL) for nanocluster of Li₂ [SiO–SnO]–2H₂, Na₂ [SiO–SnO]–2H₂ or K₂ [SiO–SnO]–2H₂. The fluctuation in charge density values demonstrates that the electronic densities were mainly located in the boundary of adsorbate/adsorbent atoms during the adsorption process. As the advantage of lithium, sodium or potassium over Si/ Sn receives its higher electron and hole motion, allowing lithium, sodium or potassium instrument to operate at higher frequencies than Si/ Sn instruments. Among these, sodium-ion batteries seem to show the most promise in terms of initial capacity.

Abstract: Hydrogen energy has great potential to become one of the clean energies of the future. The current use of hydrogen gas as an energy source still has problems, namely in the distribution and storage system. One solution to overcome these problems is to use the adsorption method. Zeolite material is considered to be a good material to be used as a storage medium for hydrogen gas. Experimental research generally still requires a fairly high cost. Therefore, we need another method that can support it. In this research, the author used the Molecular Dynamics Simulation method. The variation of temperature used in this simulation is 77, 100, 150, 195, 273, and 293 K with a variation of pressure at each temperature is 1, 2, 4, 6, 8, and 10 bar. Our simulation results are then compared with the results of experimental research conducted by other researchers. At low pressure and high temperature, the results of our simulation are close to the results of experimental research. But at high pressure and low temperature, the results of our simulation are significantly different from the results of experimental research.

Abstract: The structural stability, metallicity and hydrogen adsorption properties of Ti doped superatomic-Al₁₂C cluster have been investigated by first-principles based on density functional theory. The results show that the structural stability of Al₁₂C has been enhanced after replacing the central Al atom of icosahedra Al₁₃ configuration by carbon atom, and the most stable structure and stability of Al₁₂CTi and the lowest energy structures of Al₁₂CTi (H₂)_n (n=1-8) are searched and discussed. Moreover, the Al₁₂CTi (H₂)₆ not only exhibits strong stability according to HOMO-LUMO energy gap analysis, but also absorbs six hydrogen molecules in the absorb energy range of physical and chemical absorption, which could be considered as a candidate for hydrogen absorption materials development.

Abstract: Density functional theory was used to investigate the effect of size on the adsorption state of hydrogen atom on small cobalt particles. For this propose, we have performed series of DFT-GGA calculations on various sizes of Co clusters, between 4 and 24 atoms, and a Co FCC (100) slab, with and without hydrogen atom adsorbate. The results showed that the destabilization and the cohesive energies per atom in a metal cluster are represented as linear function of the surface-to-volume ratio of the metal clusters. In addition, the energy of the HOMO–LUMO gap from 4s and 3d valence orbitals of the cobalt atoms in the cluster is decreased with increasing in cobalt cluster size, which is size dependent parameter. We have studied the effect of the size of Co clusters and the infinite Co (100) surface, on the energy of adsorption of hydrogen atom. The calculated E_ads for hydrogen atom in our considered cobalt clusters showed decreasing behavior with increasing of the number of atoms in cluster.

Abstract: we give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside cylindric pores of adsorbents, and predict adsorption isotherms for hydrogen on A and X type zeolite at 77K. It is shown that the model reflects the peculiar features in adsorption isotherms of supercritical hydrogen in particular, a maximum in the adsorption with increasing pressure) .The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Abstract: We give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside slit pores of adsorbents, and predict adsorption isotherms for hydrogen on microporous ZSM-5 zeolite at 77K,195K and 293K. The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Abstract: In this work, the electrochemical transient behaviors of tubular steel API-P110 in buffered acidic NaCl solutions saturated with 50% H₂S and different content of CO₂ mixture gases, were investigated by single potential step chronoamperometry. Analysis of the results shows that fewer reactants take part in the reduction reaction when adding CO₂ content from 17% to 50% in 50% H₂S containing solution. Anions desorption process controls the reactant transferring process in metal-solution interface in the solution containing H₂S and CO₂. When at higher overpotential, anions desorption enhances and hydrogen absorption depresses with the increasing CO₂ content in H₂S/CO₂.

Abstract: In this theoretical study, the H2 adsorption is considered in a novel system formed by a (6,6) carbon nanotube fragment and a planar graphene layer portion, when they are separated 4.72 a.u., with both subsystems inside a cubic supercell box of 25 a.u. side. There is greater H2 adsorption inside the carbon nanotube than in the interstitial space between the graphene layer and the carbon nanotube. The results are compared with the way the H2 molecule is adsorbed upon a lonely graphene layer and inside or outside the (6,6) carbon nanotube. It is studied if in the interstitial space close to the middle point between the wall and the graphene layer the hydrogen molecule could be adsorbed with a greater binding energy that in any other case. This was not possible for the selected supercell, but there are given some suggestions to be explored (using a nanotube with smaller radii or increasing the size of the supercell), that perhaps can optimize the binding energy for H2 adsorption. A general result is that the size of the cubic supercell can be selected to confine not only hydrogen inside the carbon nanotube but also in the interstitial space between the carbon nanotube wall and the graphene layer. It is believed that the studied system or a modification of this could sooner or later be used in a competitive way in comparison with other H2 storage materials respect to the hydrogen adsorption and desorption process.

Abstract: Features of hydrogen nanostructure synthesis are described as applied to metals (Mg and Pd) and intermetallics (Mg2Ni, FeTi and LaNi5). Attention is focused on the high-energy ball milling as a universal method for hydrogen nanostructure preparation. The effect of crystallite size, absorption/desorption properties of Pd - H2, Mg2Ni - H2, TiFe - H2 and Mg - H2 systems are characterized in detail. Structural features and some physical properties of nanohydrides studied by different independent characterization methods are considered.

Abstract: We performed grand canonical Monte Carlo simulations on the series of MOFs, that are Metal-Organic Frameworks having various organic linkers and nanocube frameworks, to find out rational design and synthetic strategies toward efficient hydrogen storage materials. The adsorption amounts of hydrogen molecules showed diverse range according to the variation of parameter values. This indicated that the hydrogen adsorption was sensitive to the values of parameters corresponding to the non-bonding interactions. The optimization of the parameters was done to fit the experimental results at 77 K. After the parameterization of the potential function, we adopted this condition to predict the adsorption amount of hydrogen molecules on IRMOF-3, which has NH2 group as the substituent of hydrogen bonded to benzene ring. The calculation results showed good agreement with experimental adsorptions and we analyzed the adsorption sites of each MOF and the relationship between the adsorption characteristics and the hydrogen uptake capacity.