Ammonia (NH3) is one of the most abundant reactive nitrogen species found in air in both urban and rural areas. Titanium dioxide (TiO2) is a common photocatalyst employed in a variety of applications to remove gas-phase pollutants such as ammonia from waste streams and air. Using diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) we show that when irradiated with UV-visible light, TiO2 oxidizes atmospherically relevant levels of adsorbed NH3 to surface-adsorbed nitrogen oxides, including nitrate and nitrite. Studying the speciation of ammonia on TiO2 surfaces and photochemical intermediates and products as a function of NH3 concentration and relative humidity using DRIFTS provides insights into the reaction mechanism. The observation of products such as adsorbed nitrite suggests that photooxidation of NH3 on semiconductor surfaces may produces gas phase nitrous acid (HONO), which is of particular interest as an source of atmospheric nitric oxide (NO) and hydroxyl radical (OH), both of which contribute to ozone production.

Infrared spectroscopy studies of ammonia oxidation on TiO<sub>2</sub> surfaces as a photolytic source of nitrous acid

246th National Meeting (2013)

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Infrared spectroscopy studies of ammonia oxidation on TiO2 surfaces as a photolytic source of nitrous acid

Infrared spectroscopy studies of ammonia oxidation on TiO₂ surfaces as a photolytic source of nitrous acid