First-principles calculations engaging density functional theory (DFT) are employed to systematically study the optical characteristics of monolayer and bilayer boron nitride (BN) triphenylene-graphdiyne (Tp-BNyne) structures featuring varying lengths of C-chains. The thermal stability of Tp-BNyne structures at temperatures up to 1000 K is verified. The weak van der Waals interactions due to the small binding energies and significant interlayer distances maintain the cohesion between the layers. The investigation revealed that all Tp-BNyne structures under examination exhibit semiconductor behavior with a band gap in the range of 0.97-2.74 eV. The bilayer configurations demonstrated a narrower energy band gap in comparison to the monolayer ones. Increasing the length of C-chains leads to a reduction in the energy band gap. Delving into the optical behavior of Tp-BNyne structures under photon incidence with parallel and perpendicular polarizations, a distinct anisotropy in the optical characteristics of Tp-BNyne is revealed. The static dielectric constant increases and the optical band gap decreases with increasing C-chain length. The absorption coefficients of monolayer and bilayer Tp-BNyne structures, on the order of 107/m, demonstrate that these sheets can effectively absorb light in the visible and ultraviolet regions. These findings present Tp-BNyne sheets as promising candidates for use in photovoltaic devices to convert sunlight into electrical current, as well as for designing optical devices for ultraviolet protection. Additionally, Tp-BNyne structures are transparent materials, especially in the high-energy range.

The exceptional porous architecture of graphdiyne (GDY) renders it a potential candidate for magnetic storage media. This paper delves into the magnetic properties of GDY doped with 5d transition metal (TM) atoms via first-principles calculations. Our results divulge the stable embedding of these TM atoms within the triangular cavities of GDY, yielding a significant magneto-crystal anisotropy energy. In particular, Ta@GDY exhibits a remarkable magneto-crystal anisotropy energy value of 11.72 meV. By introducing TM atoms at the top, one could significantly change the magneto-crystal anisotropy energy value of the system, subsequently flipping the easy magnetization axis. The MAE values of Os-W3@GDY and Re-Ir3@GDY are -21.60 meV and -41.68 meV, which are expanded by a factor of 4 and 6 compared to those before the introduction of the top atom. Furthermore, we observed that the magneto-crystal anisotropy energy value of Ta@GDY is modulated by strain. Our research uncovers GDY as a promising substrate for two-dimensional magnetic materials that could be exploited in forthcoming magnetic memory devices.

Converting N2 to NH3 is an essential reaction but remains a great challenge for industries. Developing more efficient catalysts for N2 reduction under mild conditions is of vital importance. In this work, double transition metal atoms (TM=Mo, W, Nb and Ru) anchored on graphdiyne monolayer (TM2 @GDY) as electrocatalysts are designed, and the corresponding reaction mechanisms of N2 electroreduction are systematically investigated by means of first-principles calculations. The results show that the double TM atoms can be strongly anchored on the acetylenic ring of GDY and Ru2 @GDY exhibits the highest catalytic activity for NRR with a maximum free energy change of 0.55 eV through the enzymatic pathway. The significant charge transfer between the substrate and the adsorbed N2 molecule is responsible for the superior catalytic activity. This work could provide a new approach for the rational design of double-atom catalysts for NRR and other related reduction reactions.

Using extensive first principles protocols, a systematic investigation is performed to probe the oxygen reduction reaction (ORR) mechanism on nitrogen (N) doped graphynes (Gys, e. g. αGy, βGy, γGy and 6,6,12Gy) and graphdiyne (Gdy) in alkaline medium. We considered both associative and dissociative pathways, as well as two distinct intermediate forks for each of them depending on the first protonation site(s). Following the dissociative approach, the activation energy to form an O2 dissociated configuration is found as a function of the distances migrated by the O atoms over the catalyst surface and the amount of charge transferred from the C atoms linked to N. N doped αGy and 6,6,12Gy emerged as the best electrocatalyst comparing both pathways having lowest overpotentials of 0.88 and 0.82 V, respectively. The rate-limiting steps for the two different intermediate routes are observed to be dependent on the first protonation site(s) and related to the desorption of the OH radical from the sp hybridized C atom site(s) linked to N. Hence, the OH adsorption energy is identified as a descriptor for the efficiency of the ORR for the considered systems. The stabilities of the ORR intermediates are further elaborated in terms of pH and electrode potential.

The electronic properties of pristine graphdiyne nanosheet (GDY) and boron-doped graphdiyne (BGDY) were scrutinized using the first-principles calculation. Furthermore, the adsorption energy, charge transfer, and electrical conductivity variation of the 5-fluorouracil (5FU) drugs on both the GDY and BGDY sheet surfaces were reported and were employed to investigate the binding among them. The tendency of pristine GDY to 5FU drug was already identified to be negligible. Moreover, the band gap energy was changed only around 3.31% after 5FU adsorption on the GDY sheet. The adsorption energy of 5FU on the BGDY was computed in both gas and water solvent media and was about - 32.72 and - 41.96 kcal/mol, respectively. The moderate amount of solvation energy indicates the good solubility of the implemented drugs in the aqueous medium. Moreover, significant transfer of charge from the 5FU to the BGDY sheet results in a substantially positive charge for B, which is a prerequisite of the adsorption of the 5FU molecule with the suitable binding energy. In addition, after 5FU adsorption, the electrical conductivity of BGDY was increased by about 25.5%, and based on this result, the BGDY is a suitable electronic sensor for 5FU detection unlike to pristine GDY.

Graphdiyne (GDY), with uniform pores and atomic thickness, is attracting widespread attention for application in H2 separation in recent years. However, the challenge lies in the rational design of GDYs for fast and selective H2 permeation. By MD and DFT calculations, several flexible GDYs were constructed to investigate the permeation properties of four pure gas (H2, N2, CO2, and CH4) and three equimolar binary mixtures (H2/N2, H2/CO2, and H2/CH4) in this study. When the pore size is smaller than 2.1 Å, the GDYs acted as an exceptional filter for H2 with an approximately infinite H2 selectivity. Beyond the size-sieving effect, in the separation process of binary mixtures, the blocking effect arising from the strong gas-membrane interaction was proven to greatly impede H2 permeation. After understanding the mechanism, the H2 permeance of the mixtures of H2/CO2 was further increased to 2.84 × 105 GPU by reducing the blocking effect with the addition of a tiny amount of surface charges, without sacrificing the selectivity. This theoretical study provides an additional atomic understanding of H2 permeation crossing GDYs, indicating that the GDY membrane could be a potential candidate for H2 purification.

The sensing properties of 2D carbon materials are well explored for various gaseous analytes, however, the detection of toxic chemicals e.g., phosgene (Ph), thiophosgene (ThP) and phosogenoxime (PhO) are rarely studied. To the best of our literature survey, only a single study is found for the adsorption of phosgene on 2D carbon nanoflake (graphyne). This motivated us to explore the sensitivity of graphdiyne (GDY) nanoflake for the detection of phosgene and couple of its derivatives. Therefore, we have performed a density functional analysis to simulate the comparative interaction between phosgene, thiophosgene and phosogenoxime with graphdiyne nanoflake. The interaction behaviours are estimated by interaction energies, (symmetry adopted perturbation) SAPT0 analysis, (noncovalent interaction index) NCI analysis, molecular orbital analysis, natural bond orbital (NBO) charge transfer and UV-Vis absorption analysis. The obtained results demonstrate the trend in sensitivity of graphdiyne for analytes is PhO@GDY > ThP@GDY > Ph@GDY. The sensible justification for the particular observation is provided by the energy gaps between HOMO and LUMO orbitals in term of %sensitivity. The %sensitivity is in complete accord with the aforementioned trend. In addition, results suggest that graphdiyne based sensor for detecting phosgene and derivatives are better in sensitivity in comparison with already reported graphyne sensor.

Based on DFT calculations, we have explored the changes in geometric, electronic and nonlinear optical (NLO) properties of M3O and M3S (M = Li, Na and K) doped graphdiyne. The doping of superalkalis not only changes the electronic properties of GDY but also remarkably alters the NLO properties. Stabilities of doped GDY are evaluated through interaction energies. HOMO-LUMO gap, NBO, polarizability and first hyperpolarizability (βo) calculations at hybrid (B3LYP) and long-range corrected methods (CAM-B3LYP, LC-BLYP and ωB97XD) are performed for studying the NLO properties of doped GDY complexes. Significantly high values of βo are observed for all doped structures, especially for Na3S@GDY (1.36×105 au). Reduction in HOMO-LUMO gap concomitant with increase of βo value is attributed to the strong interaction of Na3S with GDY. The partial density of states (PDOS) spectra strongly support the existence of excess electrons. To rationalize the trends in first hyperpolarizability of doped GDY, two level model calculations are also performed. This study of super alkalis doped GDY will be advantageous for promoting the potential applications of the nanostructures in designing new types of electronic nanodevices and production of high performance nonlinear optical materials.

Promising applications of graphdiyne have often been initiated by theoretical predictions especially using DFT known as the most powerful first-principles electronic structure calculation method. However, there is no systematic study on the reliability of DFT for the prediction of the electronic properties of the graphdiyne. Here, we performed a study of Li adsorption on the graphdiyne using hybrid DFT with LC-ωPBE and compared the results with those of PBE, because accurate prediction of the Li adsorption is important for performance as a Li storage that was first theoretically suggested and then experimentally realized. Our results show that PBE overestimates the adsorption energy inside a pore and the barrier height at the transition state of in-plane diffusion compared to the those of LC-ωPBE. In particular, LC-ωPBE predicted almost barrier-less in-plane diffusion of Li on the graphdiyne because of the presence of both in-plane and out-of-plane π orbitals. Also, LC-ωPBE favors a high spin state due to the exact exchange energy when several Li atoms are adsorbed on the graphdiyne, whereas PBE favors a low spin state. Thus, the use of the hybrid DFT is critical for reliable predictions on the electronic properties of the graphdiyne.

We theoretically explored the adsorption and diffusion properties of oxygen and several harmful gases penetrating the graphdiyne monolayer. According to our first-principles calculations, the oxidation of the acetylenic bond in graphdiyne needs to surmount an energy barrier of ca. 1.97 eV, implying that graphdiyne remains unaffected under oxygen-rich conditions. In a broad temperature range, graphdiyne with well-defined nanosized pores exhibits a perfect performance for oxygen separation from typical noxious gases, which should be of great potential in medical treatment and industry.