N₂O + SO₂ reaction over Si- and C-doped boron nitride nanotubes: A comparative DFT study

Highlights: • The mechanisms of N₂O + SO₂ reaction are investigated over Si- and C-doped BNNTs. • Both Si- and C-doped BNNTs can be used as an efficient catalyst for the N₂O + SO₂ reaction. • The 2N₂O → O₂ + N₂ reaction needs a large activation energy over both surfaces. - Abstract: Density functional theory calculations are performed to investigate the mechanisms of N₂O reduction by SO₂ over Si- and C-doped (6,0) boron nitride nanotubes (BNNTs). According to our results, the Si or C adatom can be strongly stabilized over the vacancy defect of the BNNT. The adsorption energy of Si and C atoms over defective BNNT is calculated to be −297.3 and −333.7 kcal/mol, respectively, indicating a strong interaction between these dopant atoms and the tube surface. The N₂O reduction reaction includes the decomposition of N₂O (i.e. N₂O → N₂ + O*), followed by the reduction of O* by SO₂ molecule (i.e. SO₂ + O* → SO₃). The calculated energy barrier of the SO₂ + O* → SO₃ reaction on Si- and C-doped BNNTs is 2.4 and 5.4 kcal/mol, respectively. Moreover, the effects of tube diameter and length on the N₂O reduction are studied in detail. The disproportionation of N₂O molecules (2N₂O → 2N₂ + O₂) over both surfaces needs a quite large activation energy, which indicates the impossibility of this reaction at ambient condition. The results show that both Si- and C-doped BNNTs can be viewed as an effective green catalyst for the reduction of N₂O.