title: Synthesis and characterization of TiO₂ and TiO₂/Ag for use in photodegradation of methylviologen, with kinetic study by laser flash photolysis.
abstract: This paper reports the synthesis, characterization, and application of TiO2 and TiO2/Ag nanoparticles for use in photocatalysis, employing the herbicide methylviologen (MV) as a substrate for photocatalytic activity testing. At suitable metal to oxide ratios, increases in silver surface coating on TiO2 enhanced the efficiency of heterogeneous photocatalysis by increasing the electron transfer constant. The sol-gel method was used for TiO2 synthesis. P25 TiO2 was the control material. Both oxides were subjected to the same silver incorporation process. The materials were characterized by conventional spectroscopy, SEM micrography, X-ray diffraction, calculation of surface area per mass of catalyst, and thermogravimetry. Also, electron transfers between TiO2 or TiO2/Ag and MV in the absence and presence of sodium formate were investigated using laser flash photolysis. Oxides synthesized with 2.0 % silver exhibited superior photocatalytic activity for MV degradation.
authors.affiliation: Instituto de Química, Universidade Federal de Mato Grosso do Sul, Av. Senador Filinto Muller, 1555, CP 549, Campo Grande, MS, 79074-460, Brazil.
authors.forename: Dayana Doffinger
authors.initials: DD
authors.lastname: Ramos
authors.forename: Paula C S
authors.initials: PC
authors.lastname: Bezerra
authors.forename: Frank H
authors.initials: FH
authors.lastname: Quina
authors.forename: Renato F
authors.initials: RF
authors.lastname: Dantas
authors.forename: Gleison A
authors.initials: GA
authors.lastname: Casagrande
authors.forename: Silvio C
authors.initials: SC
authors.lastname: Oliveira
authors.forename: Márcio R S
authors.initials: MR
authors.lastname: Oliveira
authors.forename: Lincoln C S
authors.initials: LC
authors.lastname: Oliveira
authors.forename: Valdir S
authors.initials: VS
authors.lastname: Ferreira
authors.forename: Samuel L
authors.initials: SL
authors.lastname: Oliveira
authors.forename: Amilcar
authors.initials: A
authors.lastname: Machulek
mesh_terms: D002384:Catalysis; D004396:Coloring Agents; D007700:Kinetics; D008027:Light; D008670:Metals; D053758:Nanoparticles / Q000737:chemistry; D010087:Oxides; D010269:Paraquat / Q000737:chemistry*; D010782:Photolysis; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D018508:Water Purification; D014961:X-Ray Diffraction
chemical_list: D004396:Coloring Agents; D008670:Metals; D010087:Oxides; C009495:titanium dioxide; D012834:Silver; D014025:Titanium; D010269:Paraquat