Strain-tunable CO2 storage by black phosphorene and α-PC from combined first principles and molecular dynamics studies

Theoretical Investigation of Carbon Dioxide Adsorption on Li+-Decorated Nanoflakes

Recently, the capture of carbon dioxide, the primary greenhouse gas, has attracted particular interest from researchers worldwide. In the present work, several theoretical methods have been used to study adsorption of CO2 molecules on Li+-decorated coronene (Li+@coronene). It has been established that Li+ can be strongly anchored on coronene, and then a physical adsorption of CO2 will occur in the vicinity of this cation. Moreover, such a decoration has substantially improved interaction energy (Eint) between CO2 molecules and the adsorbent. One to twelve CO2 molecules per one Li+ have been considered, and their Eint values are in the range from -5.55 to -16.87 kcal/mol. Symmetry-adapted perturbation theory (SAPT0) calculations have shown that, depending on the quantity of adsorbed CO2 molecules, different energy components act as the main reason for attraction. AIMD simulations allow estimating gravimetric densities (GD, wt.%) at various temperatures, and the maximal GDs have been calculated to be 9.3, 6.0, and 4.9% at T = 77, 300, and 400 K, respectively. Besides this, AIMD calculations validate stability of Li+@coronene complexes during simulation time at the maximum CO2 loading. Bader's atoms-in-molecules (QTAIM) and independent gradient model (IGM) techniques have been implemented to unveil the features of interactions between CO2 and Li+@coronene. These methods have proved that there exists a non-covalent bonding between the cation center and CO2. We suppose that findings, derived in this theoretical work, may also benefit the design of novel nanosystems for gas storage and delivery.

Transition metal-N4 embedded black phosphorus carbide as a high-performance bifunctional electrocatalyst for ORR/OER

Designing highly active electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is an important challenge in energy conversion and storage technology. In this work, based on computational screening over doping of 23 kinds of transition metals (TMs), we use first-principles study to explore the ORR and OER activity of TM-N₄ embedded black phosphorus carbide monolayer (b-PC). The results show that its catalytic performance highly depends on the number of electrons in the d orbital and the number of valence electrons of introduced TM atom. Moreover, we found that Co-N₄-bPC (η_ORR = 0.31 V; η_OER = 0.22 V), Rh-N₄-bPC (η_ORR = 0.33 V; η_OER = 0.62 V), and Ir-N₄-bPC (η_ORR = 0.21 V; η_OER = 0.21 V) can be promising candidates as bifunctional catalysts for both the ORR and OER and can be comparable or superior to TM-N₄-graphene in terms of overpotential. They experience no structural distortion at 500 K. Moreover, the exfoliation energy of b-PC is lower than that of graphene, and these three promising candidates show much lower formation energy than TM-N₄-graphene. Our study provides a systematical method for designing and developing high performance 2D material-based single atom catalysts (SACs) beyond graphene.

Inorganic gas sensing of green phosphorene nanosheet: insights from density functional theory

Our work highlights the functionality of a novel two-dimensional phosphorene allotrope entitled green phosphorene for inorganic gas detection for the first time. Four inorganic molecules, NH3, SO2, HCN and O3, are considered as adsorbates and the adsorption conformation, adsorption energy, charge transfer, density of states, and electronic band structure are systematically scrutinized based on density functional theory. Our calculations show that the adsorption energy of O3on pristine green phosphorene is the lowest among the four considered gas molecules, suggesting that the substrate is more sensitive to O3. Significant changes in electronic structures confirm the possibility of green phosphorene for O3detection. Biaxial strains and electric fields were applied to investigate the changes in adsorption behavior. The presence of compressive strain could enhance adsorption sensitivity between O3and green phosphorene, while the tensile strain induces the dissociative adsorption that not suitable for reversible sensor. Furthermore, by controlling the orientation of external electric field, it is possible to achieve O3adsorption-desorption cycle, which is of great significance for green phosphorene in the application of reversible gas sensor.

Mild lipid extraction and anisotropic cell membrane penetration of α-phase phosphorene carbide nanoribbons by molecular dynamics simulation studies

α-PC penetrates the interior of membrane efficiently only along its zigzag direction rather than its armchair direction.