Abstract
In this work, we synthesized Ag nanoparticles on TiO2 thin films deposited on soda lime glass substrates. Ag nanoparticles were synthesized by photoreduction under UV irradiation silver nitrate solution. X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) measurements were used for physicochemical characterization. The structural study showed that all samples were polycrystalline, main phases were anatase and rutile, and no additional signals were detected after surface modification. Raman spectroscopy suggested that silver aggregates deposited on the TiO2 films could exhibit the surface plasmon resonance (SPR) phenomenon; XPS and SEM analysis confirmed TiO2 film morphological modification after photoreduction process. Photocatalytic degradation of methylene blue (MB) was studied under UV irradiation in aqueous solution, and, besides, pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. Results indicated that Ag-TiO2 showed an important increase in photocatalytic activity under UV (from 20% to 35%); finally, Ag-TiO2 thin films had kapp value 2.4 × 10−3 ± 0.003 min−1 of 1.8 times greater than the kapp value 1.3 × 10−4 ± 0.0004 min−1 of TiO2 thin films.
Highlights
Nowadays, titanium dioxide (TiO2) is one of the most important semiconductors in photocatalytic applications because of its prominent properties [1, 2]
Due to energy transfer that must be efficient during electron-hole pair separation, fast recombination of the photogenerated charge pair (e−/h+) after activation of semiconductor is an important drawback for using titanium dioxide (TiO2) as a photocatalyst, because it inhibits redox processes and reduces strongly photocatalytic efficiency [6,7,8]
We study thin film physicochemical properties through measurements of Raman spectroscopy, X-ray diffraction (XRD), and scanning electronic microscopy (SEM); the thickness of the thin films was measured through a Veeco Dektak 150 profilometer
Summary
Titanium dioxide (TiO2) is one of the most important semiconductors in photocatalytic applications because of its prominent properties (e.g., it is harmful, stable, resistant to photocorrosion, inexpensive, and has high photocatalytic properties in the degradation of different pollutants) [1, 2]. Despite all their characteristics, TiO2 has three main drawbacks: (a) fast recombination rate of photogenerated electron-hole pair, (b) low quantum yield in the photocatalytic reactions in aqueous solutions, and (c) a high bandgap value (3.2 eV, photocatalytic active only under UV irradiation) [3,4,5]. We evaluate the photocatalytic activity of Ag-TiO2 composite thin films in the degradation of methylene blue as a potential alternative in photocatalysis
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