O 2 -Mediated Synergistic Oxidation of NO and SO 2 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 SO 2 on carbonate surfaces, such as Na 2 CO 3, K 2 CO 3, etc. SO 2 surprisingly activated O 2 adsorbed on these carbonates, triggering significant adsorption and oxidation of NO under ambient temperature conditions. An intermediate species, [NO−SO 5 ], was proposed to form on the surface of Na 2 CO 3 and decompose to adsorbed NO 2 and sulfate. Subsequently, adsorbed NO 2 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.