Heterogeneous photochemistry relevant to the troposphere: H(2)O(2) production during the photochemical reduction of NO(2) to HONO on UV-illuminated TiO(2) surfaces.

Bleached out: The detection of an oxidized co-product, hydrogen peroxide, during an important tropospheric reaction, combined with the detection of photoaccelerated surface nitrate formation (a competing pathway), allows a likely mechanism to be proposed (see figure) which explains previously observed experimental stoichiometries.

Reduction of NO2 to nitrous acid on illuminated titanium dioxide aerosol surfaces: implications for photocatalysis and atmospheric chemistry.

TiO2, a component of atmospheric mineral aerosol, catalyses the reduction of NO2 to nitrous acid (HONO) when present as an aerosol and illuminated with near UV light under conditions pertinent to the troposphere.