Methylene blue degradation over M-TiO2 photocatalysts (M= Au or Pt) / Degradación de azul de metileno sobre fotocatalizadores M-TiO2 (M = Au o Pt)

Abstract

In this study it was evaluated the methylene blue degradation over TiO 2 modified by sulfation and Au or Pt addition. These materials were synthesized by photodeposition method and then were widely characterized by different techniques. In general, it was found that Au or Pt particles size distribution can be effectively controlled modifying the deposition time. It was also found that metal particle size and dye adsorption on TiO 2 surface, are important factors influencing the methylene blue degradation rate. The highest dye degradation was obtained on Au-S-TiO 2 photocatalyst prepared by using 120 min of deposition time; the highest effectiveness of this material in the methylene blue degradation can be mainly due to a combined effect between the presence of gold nanoparticles acting as a sink for the electrons photogenerated during the catalytic reaction and the better adsorption of the dye over the S-TiO 2 surface partially covered by gold particles with the largest sizes. Keywords: Methylene blue, photodegradation, sulfated TiO 2 , M-TiO 2 , photocatalysts. ResumenEn este estudio se evaluó la degradación de azul de metileno sobre TiO 2 modificado por sulfatación y adición de Au o Pt. Estos materiales fueron sintetizados a través del método de fotodeposición y caracterizados usando diferentes técnicas. En general, se encontró que la distribución de tamaño de partícula de Au o Pt se puede controlar efectivamente modificando el tiempo de fotodeposición. Se encontró también que factores como el tamaño de partícula metálica y la adsorción del colorante sobre la superficie del TiO 2 influencian de manera importante la velocidad de degradación del azul de metileno. La mayor degradación del colorante se obtuvo usando el fotocatalizador Au-S-TiO 2 preparado con un tiempo de deposición de 120 min; la alta efectividad de este material en la degradación del azul de metileno se debe principalmente a un efecto combinado entre la presencia de partículas de oro que actúan como colectores de los electrones fotogenerados durante la reacción catalítica y a la mejor adsorción del colorante sobre la superficie del S-TiO

Enhanced photocatalytic reduction of 4‐nitrophenol over Ir/CeO2 photocatalysts under UV irradiation

“…However, the material with 2.0 wt% Ir content had a higher percentage of particles with a diameter between 9 and 10 nm (21%), than that with 1.0 wt% metal ( ≈13%). The metal particle size could be a crucial aspect in the use of these nanoparticles in photocatalytic processes . The spacing of the interplanar lattices of the Ir and CeO 2 species were determined from the HRTEM image of the 1.0 wt% Ir/CeO 2 , as shown in Fig.…”

Esterification of levulinic acid via catalytic and photocatalytic processes using fluorinated titanium dioxide materials

“…On the other hand, one of the semiconductors frequently used in photocatalysis is TiO2, whose performance is strongly dependent on its optical, electronic, morphological, crystalline, and surface chemistry properties [14,15], which can be optimized by modifying the semiconductor with metallic and non-metallic elements. Modification of TiO2 with anions has been preferred over the use of cations since anions tend to form fewer recombination centers on the surface of titanium dioxide [16].…”

Glycerol oxidation by fluorinated and platinized Titania

“…In the present work, TiO 2 has been tested for glycerol oxidation, as the strategies for improve the oxidizing power and physicochemical properties of this oxide, fluorination and incorporation of platinum nanoparticles were employed. Titania is a well-known material employed in different eco-friendly processes, this is because of its stability, strong oxidizing power and relative low cost [7][8][9][10][11][12][13][14][15][16]. In order to improve the properties of TiO 2 , metal doping, fluorination and sulfation are suitable alternatives for increasing the specific surface area and the absorption of the oxide in the visible region of the electromagnetic spectrum [7,12,13].…”