Screen-printed titania photocatalytic layers made from Degussa P25 were studied in order to assess the potential of this deposition technology for the production of catalytic surfaces for airborne pollutant degradation. The deposited catalytic TiO2 layers were characterized by a low density (about 25% of the titania bulk crystal) typical of very porous films. The study was carried out using toluene at low concentration (500 nmol m-3, ~12 ppb) as model pollutant and with a relatively low UV-A irradiance level on the sample surface (200 µW cm-2). The catalyst layers were deposited on alumina, quartz and soda-lime glass substrates. The alumina and quartz samples demonstrate a good catalytic depollution activity. The soda-lime glass substrate, however, confirms to degrade the photocatalytic performance of a thermally treated titanium dioxide layer even at thickness >6 µm (~0.6 mg cm-2 layer loading). The relationship between the layer thickness and the catalytic activity was studied in the 1 to 6.8 µm range indicating an optimal 3~4 µm film thickness (0.3~0.4 mg cm-2 layer loading). Thicker layers do not show significant increases in the catalytic activity. This is consistent with the measured total optical transmittance that shows a high photon extinction beyond 5 µm of screen-printed catalytic layer. The photocatalytic activity of samples processed at temperature in the 500-900 °C range was studied showing that the post-printing thermal processing has a critical impact on the activity of the final catalytic layer. A quite good catalytic activity was demonstrated for 30 min thermal treatment up to 700 °C. These results suggest that the screen-printing process can be a promising technology for the realization of high efficiency photocatalytic materials for air depollution applications.
Photocatalytic degradation of toluene in air by screen-printed titanium dioxide layers
Strini A;Sanson A;Mercadelli E;Sangiorgi A;
2013
Abstract
Screen-printed titania photocatalytic layers made from Degussa P25 were studied in order to assess the potential of this deposition technology for the production of catalytic surfaces for airborne pollutant degradation. The deposited catalytic TiO2 layers were characterized by a low density (about 25% of the titania bulk crystal) typical of very porous films. The study was carried out using toluene at low concentration (500 nmol m-3, ~12 ppb) as model pollutant and with a relatively low UV-A irradiance level on the sample surface (200 µW cm-2). The catalyst layers were deposited on alumina, quartz and soda-lime glass substrates. The alumina and quartz samples demonstrate a good catalytic depollution activity. The soda-lime glass substrate, however, confirms to degrade the photocatalytic performance of a thermally treated titanium dioxide layer even at thickness >6 µm (~0.6 mg cm-2 layer loading). The relationship between the layer thickness and the catalytic activity was studied in the 1 to 6.8 µm range indicating an optimal 3~4 µm film thickness (0.3~0.4 mg cm-2 layer loading). Thicker layers do not show significant increases in the catalytic activity. This is consistent with the measured total optical transmittance that shows a high photon extinction beyond 5 µm of screen-printed catalytic layer. The photocatalytic activity of samples processed at temperature in the 500-900 °C range was studied showing that the post-printing thermal processing has a critical impact on the activity of the final catalytic layer. A quite good catalytic activity was demonstrated for 30 min thermal treatment up to 700 °C. These results suggest that the screen-printing process can be a promising technology for the realization of high efficiency photocatalytic materials for air depollution applications.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
