%0 Journal Article
%A Olivier Rosseler
%A Mohamad Sleiman
%A V Nahuel Montesinos
%A Andrey Shavorskiy
%A Valerie Keller
%A Nicolas Keller
%A Marta I Litter
%A Hendrik Bluhm
%A Miquel Salmeron
%A Hugo Destaillats
%B J. Phys. Chem. Lett.
%D 2013
%N 3
%P 536-541
%R 10.1021/jz302119g
%T Chemistry of NOx on TiO2 surfaces studied by ambient pressure XPS: products, effect of UV irradiation, water and coadsorbed K+
%V 4
%8 01/2013
%X <p>Self-cleaning surfaces containing TiO<sub>2</sub> nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NO<sub>x</sub> adsorbed on TiO<sub>2</sub> also was shown to form harmful gas-phase byproducts such as HONO and N<sub>2</sub>O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO<sub>2</sub> on TiO<sub>2</sub> and subsequent UV irradiation at λ = 365 nm. It is shown here that NO<sub>3-, adsorbed on TiO<sub>2</sub> as a byproduct of NO<sub>2</sub> disproportionation, was quantitatively converted to surface NO<sub>2</sub> and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO<sub>3- conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO<sub>3- in the vicinity of coadsorbed K<sup>+</sup> cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.</sub></sub></sub></p>