Reinforcing the tetracene-based two-dimensional C48H16 sheet by decorating the Li, Na, and K atoms for hydrogen storage and environmental application -A DFT study.

To meet the increasing need of energy resources, hydrogen (H2) is being considered as a promising candidate for energy carrier that has motivated research into appropriate storage materials among scientists. Thus, in this study for the first time, zig-zag and armchair edged tetracene based porous carbon sheet (C48H16) is investigated for H2 storage using the density functional theory. To explore the hydrogen storage capacity, the hydrogen molecule is initially positioned parallel to the C48H16 sheet at three different sites, resulting in lower adsorption energies of -0.020, -0.024, and -0.015 eV respectively. The Li, Na, and K atoms are decorated to improve H2 adsorption on the C48H16 sheet. The Li atom decorated C48H16 sheet has a higher binding energy value of -2.070 eV than the Na and K atom decorated C48H16 sheet. The presence of Li, Na, and K atoms on the C48H16 sheet enhance the H2 adsorption energy than the H2 on the pristine C48H16 sheet. The decrease of Mulliken charge in alkali metal atoms (Li, Na, and K atom) on the C48H16 sheet reveal that the electron is transferred from H-σ orbital to s orbital of alkali metal atoms on the C48H16 sheet, leads to the enhancement of H2 binding. Compared to H2 adsorption on Na and K atom decorated C48H16 sheet, the H2 adsorption on Li atom decorated C48H16 sheet has the maximum adsorption energy value of -0.389 eV. The obtained hydrogen storage capacity of Li, Na, and K atoms decorated C48H16 sheets are about 7.49 wt%, 7.31 wt%, and 7.14 wt% respectively for four H2 molecules, which is greater than the targeted hydrogen storage capacity of the United States Department of Energy (DOE). Thus the obtained results in this work reveal that the decorated C48H16 sheets with Li, Na, and K atom plays the potential role in the H2 storage.

Epigenetically modified nucleobases (5hmc, 5fc, and 5caC) interaction with boron and nitrogen doped porous graphene (B/N-pGr) as promising materials for biosensing application: A density functional theory calculations.

In this present work, porous graphene (pGr), boron (B-pGr), and nitrogen (N-pGr) doped porous sheets are explored as a bio-sensor device for sensing modified nucleobases (MBs) in cancer therapy using density functional theory (DFT). The obtained geometrical, energetic and electronic properties revealed that the B-pGr is highly reactive and it adsorbs MBs better than the pGr and N-pGr, because B atom holds empty p-orbitals which easily interact with partially filled p-orbital of N and O atom. Thus, the adsorption energies of 5hmc, 5caC, and 5fc on B-pGr are high rather than the pGr and N-pGr. The corresponding adsorption energies are -96.074, -77.0, and -60.721 kcal/mol for 5hmc, 5caC, and 5fc respectively. The positive signature of ΔN values (0.005 eV, 0.076 eV, and 0.047 in MBs on pGr and 0.171 eV, 0.252 eV and 0.205 eV in MBs on N-pGr) are obtained at MBs on pGr and N-pGr complex. The negative ΔN values (-0.141 eV, -0.032 eV, and -0.061 eV in MBs on B-pGr) are obtained at MBs of B-pGr. The calculated absorption values shows that the B-pGr is strongly adsorbed MBs at 342 nm. The obtained results exhibit that the B-pGr sheet retains significant therapeutic potential as a bio-sensing application for cancer therapy.

Exploring two-dimensional graphene and boron-nitride as potential nanocarriers for cytarabine and clofarabine anti-cancer drugs.

Development in two-dimensional (2D) drug-delivery materials have quickly translated into biological and pharmacological fields. In this present work, pristine graphene (PG) and hexagonal boron nitride (h-BN) sheets are explored as a drug carrier for cytarabine (CYT) and clofarabine (CLF) anti-cancer drugs using density functional theory (DFT). The obtained geometrical, energetic and electronic properties revealed that the PG sheet is more reactive and it adsorbs CYT and CLF anti-cancer drugs better than the h-BN sheet. The adsorption energies of CYT and CLF on PG sheet is -24.293 and -23.308 kcal/mol respectively, this is due to the delocalized electrons present in the PG sheet. The flow of electron direction between anti-cancer drugs and 2D sheet are calculated by ΔN, ΔEA(B), and ΔEB(A) parameters and Natural bond orbital analysis (NBO). The electronic and optical properties are calculated to understand the chemical reactivity and stability of the complex systems. The obtained results exhibit that the PG sheet retains significant therapeutic potential as a drug delivery vehicle for a drug molecule to treat cancer therapy.

Exploring the nature of interaction and stability between DNA/RNA base pairs and defective & defect-dopant graphene sheets. A possible insights on DNA/RNA sequencing.

A quantum chemical investigation is performed to understand the adsorption behaviour of DNA/RNA base pairs onto the defective (Di-Vacancy (DV) and Stone-Wales (SW)), boron (B) and silicon (Si) defect-dopant graphene (B-DV, Si-DV, B-SW, and Si-SW) sheets using density functional theory (DFT). The stability of DNA/RNA base pairs on the Si-SW sheet is found to be -80.59 kcal/mol (G-C), -70.21 kcal/mol (A-T), and -69.78 kcal/mol (A-U). The quantum theory of atoms in molecule (QTAIM) analysis concluded that the interaction of DNA/RNA base pair on Si-SW sheet has partially electrostatic and partially covalent (Si⋯N) characters. The natural bond orbital analysis (NBO), electron density difference map (EDDM), and natural population analysis (NPA) are revealed that the charge has been transferred from DNA/RNA base pair to defective and defective-dopant graphene sheet. From the time-dependent density functional theory (TD-DFT), a strong redshift is observed at 482 nm for GC-Si-SW, 494 nm for AT-Si-SW, and 497 nm for AU-Si-SW. Hence, the substantial variations in the HOMO-LUMO gap (∆EHL) and UV spectra of Si-SW sheet after the adsorption of DNA/RNA base pair can be beneficially exploited to design a new bio-sensor or DNA/RNA sequencing devices.

Modeling of Si-B-N Sheets and Derivatives as a Potential Sorbent Material for the Adsorption of Li+ Ion and CO2 Gas Molecule.

In the present exploration, a few Si-B-N derivatives are derived to adsorb Li ions and CO2 gas molecules for the potential application of metal-air batteries. The newly derived structure's bond lengths are as follows: Si=Si, 2.2 Å; Si-B, 1.9 Å; Si-N, 1.7 Å; and B-N, 1.4 Å, consistent with the experimental results of relevant structures. The stability of the newly derived structures is examined by the atom-centered density propagation study by varying the temperature from 270 to 400 K, and no structural variations are observed throughout the dynamics. Li adsorption on the Si4B2 ring has the maximum binding energy of -3.9 eV, and the result is consistent with the previous results. The rings with the 2:1 silicon-boron ratio provide strong adsorption for Li atoms. The calculated maximum electromotive force of the newly derived sheets is 0.56 V with the maximum theoretical density of 783 Wh/kg. Similarly, the maximum adsorption of CO2 on the sheet is -0.106 eV, which is considerably higher than that on graphene and its derivatives. CO2 adsorption has been carried out in the presence of water molecules to investigate the change in CO2 adsorption with the moisture (water) content, and the results show no significant change in the adsorption of CO2 with moisture. However, water has a strong interaction with the maximum interaction energy of -0.72 eV. Further, to explore the potential ability of the sheets, each sheet's edges are examined as hydrogen storage expedient and the surface as an artificial photosynthesis platform. The Si4B2 ring is more favorable for the adsorption of H atom with the chemisorption of -7.138 eV. Similarly, all of the major UV-absorption spectral peaks fall between 450 and 800 nm, which shows that the sheet can be used as an artificial photosynthesis platform.