III International Conference

PP-III-26ENHANCMENT OF PHOTOCATALYTIC ACTIVITY OF NANOSTRUCTUREDTiO 2 FILMS BY DEPOSITION OF Ag NANOPARTICLESSkorb E.V., Sviridov D.V.Belarusian State University, Minsk, BelarusE-mail: sviridov@bsu.byIt has been shown that a deposition of 3-nm silver particles radically improves the performanceof TiO 2 thin-film photocatalyst operating in air conditions. The observed effect is discussedin terms of a modification of surface states distribution resulting in lower level of recombinationlosses and higher hydrophilicity of metal-modified surface of the photocatalyst.The intrinsic hydrophilicity in oxide photocatalysts (e.g., TiO 2 ) enables an effective UVlight-driven to photodegradation of organic and bacterial contaminants in the contact with airvia mechanisms typical of aqueous suspensions of the photocatalyst that opens a variety ofpractical applications (air purification, odor control, disinfection, etc.). In the present work wedemonstrate the possibility of a radical enhancement of photoactivity of nanostructured TiO 2in air conditions by the modification of their surface with silver particles.The photocatalytic coatings were obtained by spraying the aqueous colloid of TiO 2 (withthe particles’ size of 4 nm) onto the glazed ceramic tail followed with a calcination at 450°C.The amount of photocatalytically-deposited silver was determined by Rutherfordbackscattering spectroscopy. To evaluate the photocatalytic activity, the photodegradation ofRhodamine 6G adsorbed on the photocatalyst surface was used as the probing reaction.The modification of TiO 2 films with Ag nanoparticles results in the ca. three-foldenhancement of the photocatalytic activity, this effect being observed in a rather narrowregion of Ag concentrations (1-2.5×10 15 Ag at./cm -2 ) that corresponds to the particles withmedium size of ca. 3 nm according to TEM). The chemiluminescent measurements withluminol solution evidenced higher yield of superoxide generation under UV illumination ascompared to bare TiO 2 , whereas the photoelectrochemical measurements showed that AgmodifiedTiO 2 films exhibit the ca. two-fold increase in the photocurrent generationefficiency that points to lower recombination level. It has been shown previously [1] that thedeposition of fine Ag particles (2-4 nm in size) results in “splitting” of electronic states in theforbidden zone of TiO 2 that destroys the recombination channel, this effect being almostnegligible for larger particles due to the recrystallization of the metal deposit. Another factorresponsible for the enhanced photocatalytic activity of TiO 2 -Ag films is higher inherenthydrophilicity in the metal-modified surface (the water contact angle decreases from 72 to 45°when coming from TiO 2 to TiO 2 -Ag films).References1. [1] A.I. Kulak, A.I. Kokorin, D.V. Sviridov J. Mater. Res. 2001. Vol. 16. P. 2357-2361.516