Effect of photothermal conversion on ozone uptake over deposited mineral dust

The deposited dust provides a large surface for heterogeneous ozone uptake reactions in urban regions. Prior studies have barely considered the effect of the photothermal conversion of deposited dust and underlying surface on ozone uptake. In this study, Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were selected as model mineral dusts (MDs) to evaluate the photothermal effect. With an irradiation intensity of 100 mW/cm 2 , the uptake coefficients of ozone by Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were 2.4, 30, 2.72, and 2.83 times higher than those in a dark condition. For SiO 2 and α-Al 2 O 3 , the increase in the uptake coefficient was due to the temperature increase induced by photothermal conversion. For Fe 2 O 3 and TiO 2 , photoelectric and photothermal conversion simultaneously participated in ozone uptake reactions. At 70 °C, the contribution of thermal catalysis to ozone uptake over Fe 2 O 3 and TiO 2 was approximately 55.4 % and 55.0 %, respectively. The temperature increase induced by photothermal conversion also promoted MDs' activity for ozone uptake after removing the light source (after sunset). This work proves that the ozone uptake induced by the photothermal effect of deposited MDs and the underlying surface was the primary ozone elimination pathway in urban atmospheres.