Theoretical prediction of F-doped hexagonal boron nitride: A promising strategy to enhance the capacity of adsorptive desulfurization

Miracle in "White":Hexagonal Boron Nitride

The exploration of 2D materials has captured significant attention due to their unique performances, notably focusing on graphene and hexagonal boron nitride (h-BN). Characterized by closely resembling atomic structures arranged in a honeycomb lattice, both graphene and h-BN share comparable traits, including exceptional thermal conductivity, impressive carrier mobility, and robust pi-pi interactions with organic molecules. Notably, h-BN has been extensively examined for its exceptional electrical insulating properties, inert passivation capabilities, and provision of an ideal ultraflat surface devoid of dangling bonds. These distinct attributes, contrasting with those of h-BN, such as its conductive versus insulating behavior, active versus inert nature, and absence of dangling surface bonds versus absorbent tendencies, render it a compelling material with broad application potential. Moreover, the unity of such contradictions endows h-BN with intriguing possibilities for unique applications in specific contexts. This review aims to underscore these key attributes and elucidate the intriguing contradictions inherent in current investigations of h-BN, fostering significant insights into the understanding of material properties.

Multifunctional Applications Enabled by Fluorination of Hexagonal Boron Nitride

2D materials exhibit exceptional properties as compared to their macroscopic counterparts, with promising applications in nearly every area of science and technology. To unlock further functionality, the chemical functionalization of 2D structures is a powerful technique that enables tunability and new properties within these materials. Here, the successful effort to chemically functionalize hexagonal boron nitride (hBN), a chemically inert 2D ceramic with weak interlayer forces, using a gas-phase fluorination process is exploited. The fluorine functionalization guides interlayer expansion and increased polar surface charges on the hBN sheets resulting in a number of vastly improved applications. Specifically, the F-hBN exhibits enhanced dispersibility and thermal conductivity at higher temperatures by more than 75% offering exceptional performance as a thermofluid additive. Dispersion of low volumes of F-hBN in lubricating oils also offers marked improvements in lubrication and wear resistance for steel tribological contacts decreasing friction by 31% and wear by 71%. Additionally, incorporating numerous negatively charged fluorine atoms on hBN induces a permanent dipole moment, demonstrating its applicability in microelectronic device applications. The findings suggest that anchoring chemical functionalities to hBN moieties improves a variety of properties for h-BN, making it suitable for numerous other applications such as fillers or reinforcement agents and developing high-performance composite structures.

A density functional theory study on the adsorption of different organic sulfides on boron nitride nanosheet

The adsorption of methanethiol (MT), thiophene (T), benzothiophene (BT), dibenzothiophene (DBT) on hexagonal boron nitride (h-BN) has been investigated by the framework of the density functional theory (DFT) calculations in this work. The prefer adsorption sites and interfacial angles of different sulfur compounds on the surface of the h-BN are investigated and analyzed. The adsorption energy results indicated that the adsorption of MT (Ead ≈ -6 kcal mol-1), T (Ead ≈ -10 kcal mol-1), BT (Ead ≈ -15 kcal mol-1), and DBT (Ead ≈ -21 kcal mol-1) on monolayer h-BN is physical interaction, and the value of Ead on bilayer h-BN is more than that on monolayer h-BN 0.05%. Adsorptive conformations show that sulfides prefer to be adsorbed on center B atoms rather than N atoms. Meanwhile, thiophene and its analogues tend to be adsorbed parallel on h-BN plane. Energy decomposition, natural population analysis (NPA), and electrostatic potential (ESP) analysis used to better understand the nature of adsorption on h-BN. van der Waals force plays a dominant role in adsorption process. Due to the π-π interactions, T, BT, and DBT have larger van der Waals forces than MT and the value of adsorption energy is negative correlated to the number of benzene rings. These findings are helpful for deeper understanding the adsorptive desulfurization mechanism and help develop better adsorbents for desulfurization in the future.

Group IIIA Single-Metal Atoms Anchored on Hexagonal Boron Nitride for Selective Adsorption Desulfurization via S-M Bonds

Single-atom adsorbents (SAAs) featuring maximized atom utilization and uniform isolated adsorption sites have aroused extensive research interest in recent years as a novel class of adsorption materials research. Nevertheless, it is still challenging to gain a fundamental understanding of the complicated behaviors of SAAs for adsorbing thiophenic compounds (THs). Herein, this work systematically investigated the mechanisms of adsorption desulfurization (ADS) over a single group IIIA metal atom (Ga, In, and Tl) anchored on hexagonal boron nitride nanosheets (BNNSs) via density functional theory (DFT) calculations. First, all the possible doping sites have been considered and their stabilities have been evaluated by the doped energy. DFT calculations reveal that metal atoms prefer to substitute B atoms on BNNSs rather than N atoms. Additionally, SAAs all exhibit considerably enhanced adsorption capacity for THs primarily by the sulfur-metal (S-M) bond with π-π interactions maintained. Among them, In-atom-based SAAs would be adequate to provide the highest adsorption energy (In_cen_B, -40.1 kcal mol^-1). Furthermore, from the perspective of adsorption energy, the SAAs show superior selectivity to THs than aromatic compounds due to the newly formed S-M bond. We hope that our work will manifest the design and application of SAAs in the field of ADS and shed light on a new strategy for fabricating SAAs based on BNNSs.

Using the aluminum decorated graphitic-C3N4 quantum dote (QD) as a sensor, sorbent, and photocatalyst for artificial photosynthesis; a DFT study

In this project, we have investigated the possibility of mimicking the natural photosynthesis, as well as sensing and adsorption application of aluminum decorated graphitic C₃N₄ (Al-g-C₃N₄) QDs (toward some air pollutants containing CO, CO₂, and SO₂). The results of the potential energy surface (PES) studies show that in all three adsorption processes, the energy changes are negative (-10.70 kcal mol^-1, -16.81 kcal mol^-1, and -79.97 kcal mol^-1 for CO, CO₂, and SO₂ gasses, respectively). Thus, all of the adsorption processes (mainly SO₂) are spontaneous. Moreover, the frontier molecular orbital (FMO) investigations indicate that the Al-g-C₃N₄ QD could be used as a suitable semiconductor sensor for detection of CO, and CO₂ (as carbon oxides) in one hand, and SO₂ gaseous species on the other hand. Finally, the results reveal that those QDs could be applied for artificial photosynthesis (in presence of CO₂; Δμ^h-e = 1.43 V), and for water splitting process for the H₂ generation (Δμ^h-e = 1.23 V) as a clean fuel for near future.

Ag Atom Anchored on Defective Hexagonal Boron Nitride Nanosheets As Single Atom Adsorbents for Enhanced Adsorptive Desulfurization via S-Ag Bonds

Single atom adsorbents (SAAs) are a novel class of materials that have great potential in various fields, especially in the field of adsorptive desulfurization. However, it is still challenging to gain a fundamental understanding of the complicated behaviors on SAAs for adsorbing thiophenic compounds, such as 1-Benzothiophene (BT), Dibenzothiophene (DBT), and 4,6-Dimethyldibenzothiophene (4,6-DMDBT). Herein, we investigated the mechanisms of adsorptive desulfurization over a single Ag atom supported on defective hexagonal boron nitride nanosheets via density functional theory calculations. The Ag atom can be anchored onto three typical sites on the pristine h-BN, including the monoatomic defect vacancy (B-vacancy and N-vacancy) and the boron-nitrogen diatomic defect vacancy (B-N-divacancy). These three Ag-doped hexagonal boron nitride nanosheets all exhibit enhanced adsorption capacity for thiophenic compounds primarily by the S-Ag bond with π-π interaction maintaining. Furthermore, from the perspective of interaction energy, all three SAAs show a high selectivity to 4,6-DMDBT with the strong interaction energy (-33.9 kcal mol^-1, -29.1 kcal mol^-1, and -39.2 kcal mol^-1, respectively). Notably, a little charge transfer demonstrated that the dominant driving force of such S-Ag bond is electrostatic interaction rather than coordination effect. These findings may shed light on the principles for modeling and designing high-performance and selective SAAs for adsorptive desulfurization.