Correlation preparation parameters/activity for microTiO2 decorated with SilverNPs for NOx photodegradation under LED light

TiO2 photocatalysts degrade pollutants in both the gas and liquid phase under UV radiation. To widen their application under solar and/or LED light, TiO2 surface decoration with noble metals offers a mean to achieve such a goal. Ag species as a decorating agent improve TiO2-based systems photoactivity and exhibit antibacterial properties under LED light and even in the dark. Ample literature is available on the synthesis of silver nanoparticles (Ag NPs) but few data are available on the interaction of such particles with micrometric samples. Indeed, micrometric samples pose less environmental and health concerns than the nano-sized powders widely adopted. The synthetic routes employed for Ag NPs decoration onto TiO2 clearly influence the photocatalytic activity, in particular referring to both NPs shape and fine structure. Thus, we report the preparation of Ag NPs by an electrochemical method followed by the subsequent decoration onto a micrometric TiO2 (Kronos 1077): different parameters, such as pH and the nature of physical nanoparticle dispersants were taken into account to evaluate their effect on the resulting Ag NPs features. We evaluated the photocatalytic activity towards the photodegradation of NOx under LED light, concluding that the best output was obtained by photocatalysts synthesised at basic pH.