Understanding the Novel Surface-Promoted RedOx (SPRO) Mechanism in the context of Fundamental Chemistry and Atmospheric Chemistry

An aerosol is a colloidal system of particles suspending in air. The gas-particle interface is of essential importance as it directly determines many atmospheric processes. Surface processes may have abnormal spontaneities of redox reactions described by classical theories. Recently, a novel Surface-Promoted RedOx (SPRO) mechanism has been recently discovered on typical aerosol surfaces. Through this mechanism, some thermodynamically forbidden reactions occur spontaneously in the surface environment during surface solvation. The SPRO mechanism may play several important roles in critical atmospheric processes that have not been explained earlier, such as the unclear pathway of sulfate formation and the missing sources of nitrous acid (HONO).