Photocatalytic oxidation of nitrogen monoxide using TiO2 thin films under continuous UV light illumination

Light intensity dependence of the kinetics of the photocatalytic oxidation of nitrogen(ii) oxide at the surface of TiO2

“…The respective photocatalytic oxidation pathway of NO, where water and all nitrogen compounds present at the photocatalyst surface are in equilibrium with the gas phase, is outlined in Table 2. [62][63][64] Profound objections have been raised against this pathway by Ohko and co-workers, 24,25,74 who claimed the contribution of a terminal (bridging) oxygen species, TiO 2 (O s ), and oxygen vacancies, TiO 2 (&), at the TiO 2 surface to the photocatalytic NO oxidation. The NO reaction pathway suggested by this group is presented in Table 3.…”

“…The reaction between NO and HO 2 yielding NO 2 and OH (NO + HO 2 -NO 2 + OH) is known to occur in the gas phase 75 and it cannot be excluded that the reaction likewise occurs on the TiO 2 surface. The direct formation of HNO 3 initiated by the oxidation of NO by HO 2 (NO + HO 2 -HOONO -HNO 3 ), which was proposed to occur during the photocatalytic oxidation of NO, 24,26 is known to be only a minor reaction channel of the NO + HO 2 gas phase reaction [76][77][78] and seems to be unlikely in the photocatalytic reaction. It should be emphasized that only recently experimental evidence for the suggestion that the hydroxyl radical might not even be required for the photocatalytic oxidation of NO and that the superoxide radical anion is to be regarded as the main oxidant was presented by Martinez et al 45 The possibility of homogeneous reactions in the gas phase between NO and desorbed reactive oxygen species, e.g., 1 O 2 , O 3 , OH, and HO 2 , which have been identified over irradiated TiO 2 surfaces [79][80][81][82][83][84][85][86] where they are possibly photocatalytically produced and subsequently desorbed into the gas phase, as well as secondary reactions between nitrogen compounds in the gas phase and/or at the photocatalyst surface, e.g., NO + NO 2 + H 2 O -2HNO 2 (ref.…”

Probing the activities of UV and visible-light absorbing photocatalyst powders using a resazurin-based photocatalyst activity indicator ink (Rz Paii )

“…Another important application is the use of some SC's, TiO2 in particular, to mediate the photooxidation of NOx, i.e. NO and NO2, to nitrate [4].…”

Correlation between the photocatalysed oxidation of methylene blue in solution and the reduction of resazurin in a photocatalyst activity indicator ink (Rz Paii )

“…Other work shows that TiO2 is also able to mediate the photo-oxidation of NOx, i.e. NO and NO2, to nitrate [4].…”