Changing width bandgap of TiO 2 nanoparticles incorporating GO
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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.7
Changing width bandgap of TiO2 nanoparticles incorporating GO Daniela K. Calvo-Ramos1, Marina Vega-González2, José Santos-Cruz1, Francisco Javier De Moure-Flores1 and Sandra A. Mayén-Hernández1*. 1 Facultad de Química, Posgrado en Ciencias de la Energía, Universidad Autónoma de Querétaro, 76010 Qro. México.
2
Centro de Geociencias, Universidad Nacional Autónoma de México, Querétaro, 76230 Qro. México.
*Autor de correspondencia: E-mail: [email protected] (S.A. Mayén Hernández)
ABSTRACT
Nanoparticles of titanium dioxide (TiO2), synthesized by the sonochemical technique, were mixed with different amounts of graphene oxide (GO), obtained by the improved method of Hummer, in order to modify their bandwidth. The TiO 2/OG compounds were characterized using different techniques: X-ray Diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-Vis-NIR spectroscopy. TiO2 bandgap decreased, with GO incorporation, from 3.2 to 2.72 eV when GO was present at 20 weigh percentage (TiO2/GO20%). Photodegradation experiments of methylene blue (MB) were performed with the materials to verify their photocatalytic activity. At 40 minutes, the pure TiO 2 degraded 48% of MB, whereas the compound TiO2/GO-20% degraded 88%, showing a good incorporation of both compounds and the improvement of TiO2 photocatalitic properties.
1. INTRODUCTION TiO2 is a material of great technological interest, this occurs in three crystalline phases: rutile (tetragonal structure), anatase (octahedral structure) and brookite (orthorhombic structure). TiO2, especially in anatase phase, is widely used as photocatalyst due to its optical and electronic properties, low cost, chemical stability and low toxicity [1][2][3]. A large number of researchers stablish that the TiO2 photocatalyst
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is good because it has a suitable value of bandgap (~ 3eV) [4][5][6]. The disadvantage of the energy related to the bandgap of TiO2 is, on the one hand, that it is found in the ultraviolet region of the electromagnetic spectrum, on the other hand, the visible region is wasted making the process less efficient. In recent years the incorporation of TiO2 with GO sheets has been investigated, it has been shown that the incorporation of both materials decreases the value of the bandgap for TiO2 [7]. Another advantage of the compound TiO2/GO, is that there has not been proof that this is a toxic material to the environment. In this work, different percentages of GO were incorporated to powders of TiO 2 in order to decrease the bandgap of TiO2, and photocatalitic degradation of methylene blue dye (MB) were performed. 2. MATERIALS AND METHODS TiO2 synthesis TiO2 was synthesized by sonochemical technique. A mol ratio 1:36:0.5 of titanium (from titanium isopropox
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