In this study, we use the density functional theory (DFT) calculations and the molecular dynamics (MD) simulations to investigate the performance of graphenylene-1 membrane for hydrogen (H 2 ) purification and helium (He) separation. The stability of this membrane is confirmed by calculating its cohesive energy. Our results show that a surmountable energy barrier for H 2 (0.384 eV) and He (0.178 eV) molecules passing through graphenylene-1 membrane. At room temperature, the selectivity of H 2 /CO 2 , H 2 /N 2 , H 2 /CO and H 2 /CH 4 are obtained as 3 × 10 27 , 2 × 10 18 , 1 × 10 17 and 6 × 10 46 , respectively. Furthermore, we demonstrate that graphenylene-1 membrane exhibits the permeance of H 2 and He molecules are much higher than the value of them in the current industrial applications specially at temperatures above 300 K and 150 K, respectively. We further performed MD simulations to confirm the results of DFT calculations. All these results show that graphenylene-1 monolayer membrane is an excellent candidate for H 2 purification and He separation. arXiv:1909.02112v2 [cond-mat.mtrl-sci]

From the first month of the COVID-19 pandemic, the potential antiviral properties of hydroxychloroquine (HCQ) and chloroquine (CQ) against SARS-CoV-2 suggested that these drugs could be the appropriate therapeutic candidates. However, their side effects directed clinical tests towards optimizing safe utilization strategies. The noble metal nanoparticles (NP) are promising materials with antiviral and antibacterial properties that can deliver the drug to the target agent, thereby reducing the side effects. In this work, we applied both the quantum mechanical and classical atomistic molecular dynamics approaches to demonstrate the adsorption properties of HCQ/CQ on Ag, Au, AgAu, and Pt nanoparticles. We found the adsorption energies of HCQ/CQ towards nanoparticles have the following trend: PtNP > AuNP > AuAgNP > AgNP. This shows that PtNP has the highest affinity in comparison to the other types of nanoparticles. The (non)perturbative effects of this drug on the plasmonic absorption spectra of AgNP and AuNP with the time-dependent density functional theory. The effect of size and composition of NPs on the coating with HCQ and CQ were obtained to propose the appropriate candidate for drug delivery. This kind of modeling could help experimental groups to find efficient and safe therapies.

In order to separate a mixture of hydrogen ($$\text {H}_{2}$$ H 2 ) and carbon dioxide ($$\text {CO}_{2}$$ CO 2 ) gases, we have proposed a new approach employing the graphdiyne-like membrane (GDY-H) using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. GDY-H is constructed by removing one-third diacetylenic ($${{-}\text {C}{\equiv}\text {C}{-}\text {C}{\equiv}\text {C}{-}}$$ - C ≡ C - C ≡ C - ) bonds linkages and replacing with hydrogen atoms in graphdiyne structure. Our DFT calculations exhibit poor selectivity and good permeances for $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 gases passing through this membrane. To improve the performance of the GDY-H membrane for $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 separation, we have placed two layers of GDY-H adjacent to each other which the distance between them is 2 nm. Then, we have inserted 1,3,5-triaminobenzene between two layers. In this approach, the selectivity of $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 is increased from 5.65 to completely purified $$\text {H}_{2}$$ H 2 gas at 300 K. Furthermore, GDY-H membrane represents excellent permeance, about $$10^8$$ 10 8 gas permeation unit (GPU), for $$\text {H}_{2}$$ H 2 molecule at temperatures above 20 K. The $$\text {H}_{2}$$ H 2 permeance is much higher than the value of the usual industrial limits. Moreover, our proposed approach shows a good balance between the selectivity and permeance parameters for the gas separation which is an essential factor for $$\text {H}_{2}$$ H 2 purification and $$\text {CO}_{2}$$ CO 2 capture processes in the industry.

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In this study, we demonstrate that defected h-BN (1B-3N and 1N-3B defects) can be used as a suitable membrane for hydrogen purification and helium separation using density functional theory (DFT) calculations and molecular dynamics simulations (MD). At 300 K, DFT calculations show that the selectivity of H 2 /CO 2 , H 2 /N 2 ,