Nitrates experience photolysis at ? > 300 nm to form NOx, while adsorbed nitrate on non-conductive surfaces does not appear to be photoactive. In contrast, photolytic reaction and production of NOx are observed when the nitrate is adsorbed onto a semiconductive material. In this second case, the semiconductive metal oxide can absorb the light and trigger a photochemical reaction to produce NOx. In this work, we studied the rate law and rate constant of the heterogeneous photochemistry of nitrates on metal oxides depending on both the band gap of the metal oxide and the adsorption coordination of nitrate onto the surface. We determined the pseudo-first order kinetic constant of the heterogeneous photochemistry of adsorbed nitric acid on semiconductive metal oxides, specifically, ?-Al2O3, TiO2, a-Fe2O3, and ZnO, and a control insulator SiO2. In addition, quantification of gas-phase nitrogen oxide products from each reaction is reported.

Kinetic study of the heterogeneous photochemistry of nitric acid on semiconductive metal oxides

244th National Meeting (2012)

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