Water Purification by 2-Dimensional Dodecagonal Nitride and Graphenylene via First Principles Calculations.

2 dimensional (2D) dodecagonal boron nitride (D_BN) and graphenylene are being investigated to understand their potential applications in water purification. First principle calculations are performed to evaluate the water purification properties of D_BN and graphenylene. It is found that Na+ exothermically adsorbs on pores in D_BN, where the transition state energy via pores is calculated to be 0.03 eV. This indicates that Na+ can pass through D_BN pores more selectively than water molecules and other ions. In contrast, in the case of graphenylene, Na+ is repelled, and H2 O exothermically adsorbs on pores, where the transition state energy via pores is calculated to be 1.00 eV. Therefore, this demonstrates that D_BN exhibits an excellent potential for ion-sieving membranes, while graphenylene exhibits an excellent potential for reverse osmosis membranes. Consequently, this study provides valuable insights into the potential use of D_BN and graphenylene in water purification applications.

Enhancement of thermoelectric performance in graphenylene nanoribbons by suppressing phonon thermal conductance: the role of phonon local resonance.

Based on the method of non-equilibrium Green's function, we investigate the thermal transport and thermoelectric properties of graphenylene nanoribbons (GRNRs) with different width and chirality. The results show that the thermoelectric (TE) performance of GRNRs significantly increases with decreasing ribbon width, which stems from the reduction of thermal conductance. In addition, by changing the ribbon width and chirality, the figure of merit (ZT) can be controllably manipulated and maximized up to 0.45 at room temperature. Moreover, it is found that theZTvalue of GRNRs with branched structure can reach 1.8 at 300 K and 3.4 at 800 K owing to the phonon local resonance. Our findings here are of great importance for thermoelectric applications of GRNRs.

Atomistic understanding on desalination performance of pristine graphenylene nanosheet membrane at high applied pressures.

Molecular dynamics (MD) simulations are conducted to assess pristine graphenylene membranes' effectiveness in seawater desalination, explicitly focusing on their salt rejection and water permeability capabilities. This study investigates the potential of the graphenylene for separation of the Na+ as monovalent cation, in order to evaluate its further application for separation of the other type of contaminants. To this end, the pristine graphenylene nanosheet is introduced into the simulation box which included the water molecules, sodium and chlorine ions. Subsequently, MD simulations were conducted by applying different amounts of external pressures in which the temperature changes are investigated as another effective parameter in water permeability and salt rejection properties. Furthermore, the water density map, radial distribution functions, and water density elucidate the performance of the considered membrane in the presence of water molecules, Na+ ions, and Cl- ions. The optimum performance of the pristine graphenylene for seawater desalination is achieved at P = 400 MPa and T = 298 K that results in the water flux of 2920 L/m2 h bar and 98.8 % salt rejection. The pristine graphenylene nanosheet shows significant potential in effectively separating salt ions, which has elucidated its importance and subsequently, the functionalized membrane for this application.

Efficient separation of He/CH4 mixture by functionalized graphenylene membranes: A theoretical study.

In this work, we prepared two types of functionalized pore on pristine graphenylene membrane to study and compare the He/CH4 separation performance employing molecular dynamics (MD) simulation. The gas molecules transport through the membranes was monitored during the simulations. The results indicated that methane molecules cannot pass through the membranes under applied conditions, while helium molecules simply penetrate through, which verifies the ultrahigh selectivity of helium over methane molecules. The maximum helium permeance of about 1 × 107 GPU was obtained through the functionalized graphenylene membrane at room temperature, which is much higher than graphenylene membrane. As a consequence, the functionalized graphenylene membrane can supply both high permeance and selectivity for helium separation. The van der Waals (vdW) interactions between gas molecules and the surface of the membrane was also investigated. We further conducted the potential of mean force (PMF) calculations to study the permeation of gas molecules across the membrane. Although methane molecules, due to more powerful interactions between them and the surface of the membrane, adsorb on the membrane surface, face higher energy barrier near the membrane nanopore. In reality, adsorption prefers methane molecules on the membrane surface, while diffusion favors helium over methane molecules through the nanopores. The functionalized graphenylene membrane is expected to be able to be employed as a promising membrane for a highly efficient helium purification system.

Theoretical study of electronic and nonlinear optical properties of novel graphenylene-based materials with donor-acceptor frameworks.

A new functionalized graphenylene-based structure was designed by adsorbing of alkali metals M3 and superalkali M3O (M = Li, Na, K) on graphenylene (BPC) surface. The spectral data show that the spectral properties of the M3O@BPC system are very similar because the two-dimensional material plays a major role in the main transition. However, for M3@BPC system, the spectral shapes of the three systems show significant changes compared to each other because the different alkali metals play a major role in the main transition process. The calculation results show that the introduction of superalkali does not significantly increase the first polarizability; however, the introduction of alkali metals can obtain considerable nonlinear optical materials. For M3@BPC system, the first hyperpolarizability increases significantly when heavier alkali metal is introduced into the two-dimensional structure, which is found to be 866,290.9 au for K3@ BPC. A two-level model and first hyperpolarizability density can explain the large first polarizability of these systems.

Theoretical study of collision dynamics of fullerenes on graphenylene and porous graphene membranes.

A comparative study regarding the behavior of graphene, porous graphene and graphenylene monolayers under high energy impact is reported. Our results were obtained using a computational model constructed to perform investigations of the dynamics of high velocity fullerenes colliding with free standing sheets of those materials. We employed fully reactive molecular dynamics simulations in which the interatomic interactions were described using ReaxFF force field. During the simulations, free standing monolayers of the investigated materials were submitted to collision with a C60 fullerene molecule at impact angles within the range 0°≤θ≤75°. We considered kinetic energies in the range 0eV≤Ek≤1500eV, that corresponds to a projectile velocity v in the range 0Å/fs≤v≤0.2Å/fs. Also, the failure dynamics of each one of the 2-dimensional materials is described in a comparative analysis in which relevant differences and unique features observed in the mechanical stress dissipation processes are highlighted. Finally, performing hundreds of simulations we were able to map many possible scenarios for these collisions and to construct diagrams that elucidate, for each one of the materials, the possible behaviors under the action of a highly energetic C60 projectile as a function of energy and incident angle.