O₂-Mediated Synergistic Oxidation of NO and SO₂ on Carbonate Surfaces

Carbonate minerals, as key components of atmospheric dust, play a critical role in neutralizing acidic pollutants. Their heterogeneous reaction behavior under ambient conditions, particularly at room temperature and without added oxidants, remains poorly understood. In this study, we found synergistic oxidation of NO and SO₂ on carbonate surfaces, such as Na₂CO₃, K₂CO₃, etc. SO₂ surprisingly activated O₂ adsorbed on these carbonates, triggering significant adsorption and oxidation of NO under ambient temperature conditions. An intermediate species, [NO-SO₅], was proposed to form on the surface of Na₂CO₃ and decompose to adsorbed NO₂ and sulfate. Subsequently, adsorbed NO₂ can react with surface oxygen sites to generate adsorbed nitrate. This finding fills the gap in the interaction mechanism between nitrogen and sulfur species on carbonate particles, revealing the significant catalytic role of carbonate in promoting oxidation processes within complex polluted atmospheric environments.