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.