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In this paper, the hydrogen storage performance of Sc (Ti, Li)-modified Ψ -graphene (Ψ -g) is investigated by density functional theory (DFT). Sc and Ti can be stably adsorbed on Ψ -g with the binding energies of 4.78 eV and 4.83 eV, respectively. Li atoms can also be stably absorbed on B-doped Ψ -g with the binding energy of 2.51 eV. In addition, Sc and Ti atoms attached on Ψ -g can adsorb up to ten and eight hydrogen molecules, and the hydrogen gravimetric storage capacity reaches 7.93 wt.% and 6.20 wt.%, respectively. Li atoms attached on B-doped Ψ -g can adsorb up to eight hydrogen molecules with the hydrogen gravimetric storage capacity 9.32 wt.%, all meeting DOE standards. On the whole, Bader charge analysis shows that the charge is transferred from C atoms to H atoms, which is more conducive to hydrogen adsorption. All the researches prove that the Sc, Ti-decorated Ψ -g and Li-decorated B-doped Ψ -g are potential hydrogen storage materials. [ABSTRACT FROM AUTHOR]

Based on density functional theory, the hydrogen storage performance of boron-doped porous graphene modified with beryllium or vanadium metal was studied. By changing the doping amount of boron and the doping sites, it was found that metals have the highest adsorption energy on B 16 -PG and B 22 -PG doped with a pair of boron atoms and two pairs, respectively. Be 2 –B 16 -PG and Be 2 –B 22 -PG can adsorb six hydrogen molecules, the corresponding hydrogen storage capacities are 7.30 wt% and 7.40 wt%, respectively. V 2 –B 16 -PG can adsorb up to ten hydrogen molecules, with the hydrogen storage energy reaching 8.07 wt%. This shows that boron doping can effectively improve the hydrogen storage performance of the system. [Display omitted] • The hydrogen storage properties of boron-mixed porous graphene were studied by DFT. • E ad (H 2) of Be 2 –B 22 -PG are in the range of 0.09–0.30 eV. • E ad (H 2) of V 2 –B 16 -PG are in the range of 0.34–0.50 eV. • The gravimetric capacity of Be 2 –B 22 -PG system reaches 7.40 wt%. • The gravimetric capacity of V 2 –B 16 -PG system reaches 8.07 wt%. [ABSTRACT FROM AUTHOR]

By density functional theory (DFT), a new C-doped boron nitrogen nanochain with lithium decoration was designed for hydrogen storage. The lithium adsorption behavior of BN chains with different doping ratio and methods of carbon atoms was systematically studied. The results proved that the metal binding energy could be effectively improved after replacing the N atom in the pure BN chain with C. When a lithium atom was adsorbed, the metal binding energy of the B 8 N 7 C nanochain was the highest, reaching 3.79 eV, much higher than the cohesive energy of Li, which avoided lithium cohesion. When two lithium atoms were adsorbed, the metal binding energy of the B 6 N 5 C nanochain was the highest, reaching 2.67 eV. For carbon doping ratios of 6.11 %, 6.99 %, 8.18 %, 9.84 %, 12.35 % and 16.58 %, each lithium atom could adsorb almost four H 2 molecules, and the average binding energy was about 0.14 eV. When the carbon doping ratio was 16.58 %, the maximum H 2 mass ratio of 18.68 wt% was reached. These results all indicate that the Li-BCN series nanochains are a very promising hydrogen storage material. [Display omitted] • The hydrogen storage characteristics of nanochains are studied by DFT and MD. • When a lithium atom is adsorbed, the average binding energy of Li is about 3.6 eV. • When two lithium atoms are adsorbed, the average binding energy is around 2.4 eV. • The maximum weight storage capacity for adsorbing one lithium atom is 10.16 wt%. • The maximum weight storage capacity for adsorbing two lithium atoms is 18.68 wt%. [ABSTRACT FROM AUTHOR]

The optimized 2 × 2 × 1 supercell of H 2 @Li@FNnets by a DFT study. Pink indicates Boron; gray, Carbon; white, Hydrogen; purple, Lithium. [Display omitted] • A novel periodic networks of crossed nanotubes with fullerene junctions is designed. • Both (Li,Na,Be)-decoration and B-doping improve hydrogen adsorption. • Li, Na, Be can disperse stably on the surface of B-FNT-nets proved by DFT and MD. • Charge transfer from adatoms to the substrate leads to strong polarization of H2. • HGDs are 13.95, 10.09, and 10.85 wt% for (Li, Na, Be)-decorated FNT- nets by DFT. Novel carbon-based periodic networks of crossed nanotubes with fullerene junctions (FNT-nets) has been designed as a potential solid hydrogen storage medium. Density functional theory calculations and molecular dynamics simulations have been performed to explore the structural stability and the hydrogen-storage potential of FNT-nets. Via the B-doping strategy, the binding energies of the alkali metal (Li, Na) and alkaline-earth metal (Be) were effectively improved to 2.47, 2.10, and 1.98 eV, respectively. The Li, Na, and Be atoms could be firmly dispersed atomically on the surface of B-FNT-nets, donating 0.732, 0.711, and 1.455 e to the substrate. The positive charge on the metal proved to be proportional to the strength of H 2 polarization. Overall, up to four hydrogen molecules could be stored around one lithium with an average adsorption energy of 0.20 eV. Five hydrogen molecules were found to be around sodium and beryllium atoms with 0.17 and 0.27 eV in the range of reversible physical adsorption. The corresponding theoretical uptakes for Li@C 158 B 22 , Na@C 132 B 24 , and Be@C 132 B 24 systems (13.95, 10.09, and 10.85 wt%, respectively) exceed the ultimate goal (6.5 wt%) as laid out by US Department of Energy. Our results reveal that the FNT-nets are good candidates for hydrogen storage. [ABSTRACT FROM AUTHOR]