TY - JOUR AU - Olivier Rosseler AU - Mohamad Sleiman AU - V Nahuel Montesinos AU - Andrey Shavorskiy AU - Valerie Keller AU - Nicolas Keller AU - Marta I Litter AU - Hendrik Bluhm AU - Miquel Salmeron AU - Hugo Destaillats AB -

Self-cleaning surfaces containing TiO2 nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NOx adsorbed on TiO2 also was shown to form harmful gas-phase byproducts such as HONO and N2O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO2 on TiO2 and subsequent UV irradiation at λ = 365 nm. It is shown here that NO3-, adsorbed on TiO2 as a byproduct of NO2 disproportionation, was quantitatively converted to surface NO2 and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO3- conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO3- in the vicinity of coadsorbed K+ cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.

BT - J. Phys. Chem. Lett. DA - 01/2013 DO - 10.1021/jz302119g IS - 3 N2 -

Self-cleaning surfaces containing TiO2 nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NOx adsorbed on TiO2 also was shown to form harmful gas-phase byproducts such as HONO and N2O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO2 on TiO2 and subsequent UV irradiation at λ = 365 nm. It is shown here that NO3-, adsorbed on TiO2 as a byproduct of NO2 disproportionation, was quantitatively converted to surface NO2 and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO3- conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO3- in the vicinity of coadsorbed K+ cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.

PY - 2013 SP - 536 EP - 541 T2 - J. Phys. Chem. Lett. TI - Chemistry of NOx on TiO2 surfaces studied by ambient pressure XPS: products, effect of UV irradiation, water and coadsorbed K+ VL - 4 ER -