A surface-promoted redox reaction occurs spontaneously on solvating inorganic aerosol surfaces.

A surface-promoted sulfate-reducing ammonium oxidation reaction was discovered to spontaneously take place on common inorganic aerosol surfaces undergoing solvation. Several key intermediate species—including elemental sulfur (S), bisulfide (HS), nitrous acid (HONO), and aqueous ammonia [NH]—were identified as reaction components associated with the solvation process. Depth profiles of relative species abundance showed the surface propensity of key species.