engleski

Black TiO2 nanotube arrays decorated with Ag nanoparticles for enhanced visible-light photocatalytic oxidation of salicylic acid

In this work novel form of black TiO2-based photocatalysts for water purification was prepared by combination of two effects ; decoration with Ag nanoparticles and hydrogenation of decorated TiO2 nanotube arrays. Such form of photocatalyst considerably exceed the photocatalytic properties of commercial TiO2 P25. The superior photocatalytic performances of the photocatalyst, particularly under visible irradiation, was explained by the combined effect of a local surface plasmon resonance (LSPR) due to Ag nanoparticles and creation of additional energy levels in band-gap of TiO2 due to Ti3+ states at nanotube surfaces which induced band-gap narrowing. The presence of Ag also positively influenced on charge separation of created electron-holes pairs. The black TiO2- based photocatalysts were shown high efficiency for degradation of salicylic acid, a typical pollutant in precipitation, surface waters and as a constituent of humic material in drinking waters due to its widespread use in dyestuff, resins and aspirin production. The findings are well supported by the complex kinetic model which allowed a separate study of contribution from salicylic acid photolysis, photocatalysis in UVB, UVA and visible part of applied simulated solar irradiation on overall degradation rate. The synergy of several effects was quantified through the factor of synergy, fSyn. Obtained results support our hypothesis studied thoroughly in this paper, that combination of deposition nobel-metal nanoparticles (Ag) at TiO2 surface subsequently annealed in hydrogen atmosphere significantly increase photocatalytic efficiency. The novel design presents a solid base for development of more efficient photocatalytic reactors for large-scale with a long-term activity.

black TiO2 nanotubes arrays ; Ag decoration ; salicylic acid ; photodegradation ; solar irradiation ; kinetic model

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