RESUMEN

DFT calculations were used to study the quantum capacitance of pure, B/Al/Si/N/P-doped, and defective γ-graphyne. Due to the direct relationship between capacitance and electronic states around the Fermi level, structures' electronic properties were evaluated by DOS plots. The results of integrated specific quantum capacitance in the range of water stability potential show an improvement of capacity in each p and n-type doping. The calculated cohesive energies of doped structures reflect the stability enhancement. Also, the stability/capacitance of single and double vacancies in two distinct positions (sp and sp2) were examined. The results illustrate stability retention and quantum capacitance improvement of these defective structures. Among the doped structures, the maximum quantum capacitance is 2251.10 F/gr belonging to the aluminum doped structure (in the sp position). For the defective structures, the maximum quantum capacitance is 4221.69 F/gr belonging to removing two sp carbon atoms. These quantum capacitances significantly improved compared to the pristine structure (1216.87 F/gr) and many other structures. These stunning results can contribute to the design of appropriate structures as electrode materials for high-efficiency supercapacitors.

RESUMEN

Spherical nanocarriers can lead to a bright future to lessen problems of virus infected people. Spherical polyethylene glycol (PEG) and spherical silica (SiO2) are novel attractive nanocarriers as drug delivery agents, especially they are recently noticed to be reliable for antiviral drugs like anti-HIV, anti-covid-19, etc. Lamivudine (3TC) is used as a first line drug for antiviral therapy and the atomic view of 3TC-PEG/SiO2 complexes enable scientist to help improve treatment of patients with viral diseases. This study investigates the interactions of 3TC with Spherical PEG/SiO2, using molecular dynamics simulations. The mechanism of adsorption, the stability of systems and the drug concentration effect are evaluated by analyzing the root mean square deviation, the solvent accessible surface area, the radius of gyration, the number of hydrogen bonds, the radial distribution function, and Van der Waals energy. Analyzed data show that the compression of 3TC is less on PEG and so the stability is higher than SiO2; the position and intensity of the RDF peaks approve this stronger binding of 3TC to PEG as well. Our studies show that PEG and also SiO2 are suitable for loading high drug concentrations and maintaining their stability; therefore, spherical PEG/SiO2 can reduce drug dosage efficiently.

Asunto(s)

Antivirales , Lamivudine , Humanos , Dióxido de Silicio , Polietilenglicoles , Simulación de Dinámica Molecular

RESUMEN

In this work, by density functional theory (DFT) calculations, sp-sp2-hybridized boron-doped graphdiyne (BGDY) nanosheets have been investigated as an anode material for sodium storage. The density of states (DOS) and band structure plots show that substituting a boron atom with a carbon atom in an 18-atom unit cell converts the semiconductor pristine graphdiyne (GDY) to metallic BGDY. Also, our calculations indicate that, due to the presence of boron atoms, the adsorption energy of BGDY is more than that of GDY. The diffusion energy barrier calculations show that the boron atom in BGDY creates a more suitable path with a low energy barrier for sodium movement. This parameter is important in the rate of charge/discharge process. On the other hand, the projected density of states (PDOS) plots show that sodium is ionized when adsorbed on the electrode surface and so Na-BGDY interaction has an electrostatic character. This type of interaction is necessary for the reversibility of adsorption in the discharge mechanism. Finally, the calculation of the theoretical capacity shows an increase in BGDY (872.68 mAh g-1) in comparison with that in GDY (744 mAh g-1). Thus, from comparison of different evaluated parameters, it can be concluded that BGDY is a suitable anode material for sodium-ion batteries.

RESUMEN

The electronic properties, adsorption energies and energy barrier of sodium ion diffusion in B-doped graphyne (BGY) are studied by density functional theory (DFT) method. If some carbon atoms in pristine graphyne (GY) are substituted by boron atoms (one substitution per unit cell in this work), BGY is obtained, and the band structure and density of state (DOS) plots indicate a transition from a semiconductive state for GY to a metallic state for BGY. The calculated adsorption energy shows an improvement in the trigonal-like pore (T site) and hexagonal ring (H site) adsorption of BGY compared to the corresponding analog sites in GY. The comparison of projected density of state (PDOS) plots before and after adsorption reveals charge transfer from sodium to nanosheets. Therefore, the interaction between adsorbed sodium atom and BGY/GY has ionic character and not covalent. This phenomenon is important for the reversible sodium adsorption in secondary batteries. Moreover, PDOS plots show that the electron transfer from sodium atom to host structure in BGY is more than in GY, which is in agreement with adsorption energies. According to diffusion energy barrier calculations, boron atoms in BGY structure provide low energy paths for sodium ions diffusion. We estimate a theoretical capacity of 751 mA h g-1 for the maximum sodium adsorption on BGY (without cluster formation). Therefore, BGY is a promising anode material for sodium ion batteries (SIBs).