A DFT study on NO reduction to N2O using Al- and P-doped hexagonal boron nitride nanosheets

Using the dispersion-corrected DFT calculations, the catalytic reduction of NO molecules to N₂O is investigated over Al- and P-doped hexagonal boron nitride nanosheets (h-BNNS). It is found that NO dissociation over both these surfaces needs a very large energy barrier, which indicates it cannot proceed at normal temperature. In contrast, the results show that NO molecules can be easily reduced into N₂O via a dimer mechanism. The obtained activation energies reveal that the catalytic activity of Al-doped h-BNNS is better than that of P-doped one, mainly due to the moderate coadsorption energies of NO molecules over this surface.

Oxidation of SO2 over C-doped boron nitride nanosheets: The role of C-doping, and solvent effects

In this work, density functional theory calculations are performed to examine the catalytic oxidation of SO₂ in the presence of O₂ molecule over carbon-doped hexagonal boron nitride nanosheets (h-BNNSs). The SO₂ oxidation over these surfaces is characterized as a two-step mechanism; (a) SO₂ + O₂ → SO₃ + O* and (b) SO₂ + O* → SO₃. According to the obtained results, the activation energies and reaction mechanism depend greatly on the substitution site of the C-doped h-BNNS. That is, the catalytic activity of C atom located on top of the B-vacancy site of h-BNNS is larger than that of on top of the N-vacancy. Moreover, it is found that the energy barriers for the oxidation of SO₂ are considerably decreased in an aqueous solution. For a given substrate, the activation energy for the oxidation of H₂SO₃ is much larger than that of SO₂, suggesting that the direct conversion of SO₂ to SO₃ should be the main reaction pathway for the oxidation of SO₂. The results of present study could contribute to design highly active BN-based catalysts to oxidize SO₂ molecule.

A template-free solvent-mediated synthesis of high surface area boron nitride nanosheets for aerobic oxidative desulfurization

Hexagonal BN nanosheets with high surface area are developed via methanol-mediated synthesis, presenting outstanding catalytic performance in aerobic oxidative desulfurization.

The healing of B- or N-vacancy defective BNNTs by using CO molecule: a DFT study

Boron or nitrogen vacancies of BNNTs can be effectively healed by CO at ambient temperature.

Theoretical prediction of the mechanisms for defect healing or oxygen doping in a hexagonal boron nitride (h-BN) sheet with nitrogen vacancies by NO2 molecules

Healing defects in hexagonal boron nitride (h-BN sheet) or doping it with oxygen can modify or restore its physical properties, which would increase its range of potential applications. Thus, it is very important to find an efficient method of healing or a BN sheet or doping it with oxygen. In this work, using density functional theory (DFT) calculations, we identified a mechanism for healing h-BN sheets with nitrogen vacancies (VN) or doping BN sheets with oxygen using NO2 molecules. The results indicate that such reactions involve three steps: (1) the chemisorption of NO2, (2) the incorporation of the N or O atom of NO2 into the defective h-BN sheet, and (3) the removal of the adsorbed O atom or NO molecule. We found that the proposed mechanism is theoretically possible and has the following advantages. First, the barrier is about 0.60 eV for the formation of the O-doped h-BN sheet. For the healing process, because the energy released during NO2 chemisorption (-4.94 eV) completely offsets the subsequent barrier (1.17 eV), a perfect h-BN sheet can easily be achieved by using NO2 and an h-BN sheet with VB defects as reactants. Second, no catalyst is needed, and thus there is no need for a purification step to remove the catalyst. Third, NO2, a toxic gas, can be used as a reactant and will then be reduced to O2 or NO. Fourth, NO2 shows high selectivity for vacancy defect sites. Our findings show that this is an effective theoretical method of synthesizing O-doped h-BN sheets or of healing defective h-BN sheets, which should prove useful in the design of h-BN sheet-based devices.