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

Abstract

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.

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

“…The criteria for the convergence of the total energy is set to be 1.0 × 10 –8 a.u. (≈6.3 × 10 –6 kcal mol –1 ), whereas for the geometry optimization, the maximum force and maximum displacement of atoms are set to be 0.00045 and 0.0018 a.u., respectively, which is accurate enough to get a total energy and energy gradient for similar systems. ,, Furthermore, vibrational analysis has been conducted to ensure that the obtained species are true local minima on the potential energy surface (Table S6). The zero point energy corrections have been also considered after the vibrational analysis.…”

“…In addition to heteroatom doping, ,, metal atom doping is another efficient way to enhance ADS performance. ,− Metals elements are responsible for the enhanced ADS performance as they can be regarded as adsorption sites to form strong sulfur-metal (S–M) coordination bonds. As reported, the lone-pair electrons of S atoms in THs tend to interact with s orbitals in metals, whereas the aromatic compounds cannot form such special interactions. ,, Therefore, adsorbents making use of the S–M coordination bonds could selectively remove THs from diesel fuel.…”

“…53 SAAs are a novel category of adsorbents with isolated single-atom centers dispersed on support materials. 52,53 As one of the group IIIA elements, Al atoms possess similar valence electrons to B atoms. It is predicted that other group IIIA elements like Ga, In, and Tl may have the same tendency.…”

“…More recently, our group found that Al single-atom adsorbents (SAAs) based on BNNSs have excellent adsorption performance for dibenzothiophene through S–Al coordination . SAAs are a novel category of adsorbents with isolated single-atom centers dispersed on support materials. , As one of the group IIIA elements, Al atoms possess similar valence electrons to B atoms. It is predicted that other group IIIA elements like Ga, In, and Tl may have the same tendency.…”

Editorial for the Special Issue on “Boron Nitride-Based Nanomaterials”

“…Single atom adsorbents (SAAs) are a novel class of materials that have great potential in various fields, especially in the field of adsorptive desulfurization. Li et al investigated the mechanisms of adsorptive desulfurization over a single Ag atom supported on defective hexagonal boron nitride nanosheets via density functional theory calculations [ 3 ]. These Ag-doped hexagonal boron nitride nanosheets all exhibit enhanced adsorption capacity for thiophenic compounds primarily by the S-Ag bond.…”