Ag/GO/TiO₂ nanocomposites: the role of the interfacial charge transfer for application in photocatalysis

Abstract

TiO2 semiconductor nanoparticles (NPs) in the anatase phase have presented limitations of application in photocatalysis, mainly due to the fast recombination of photoexcited electrons. The combination with other nanoparticles/nanostructures has been shown to be a promising solution for increasing photocatalytic efficiency. In this work, titanium dioxide (TiO2) nanoparticles in different crystalline phases were prepared through a rapid microwave-assisted synthesis and modified by silver nanoparticles (Ag) and graphene oxide (GO). The samples were characterized by x-ray diffraction, transmission electron microscopy, energy dispersive x-ray spectroscopy, infrared spectroscopy and gas adsorption. Crystalline anatase NPs were obtained in basic conditions (pH = 8) while in acidic conditions (pH = 1), single-crystalline rutile NPs were formed. Different previous drying methods: oven and freeze-drying used led to a differentiation in crystallographic phases obtained. Anatase TiO2 and anatase-rutile mixture NPs calcined at 400 °C showed properties as high specific surface area, crystallinity and reduced electron–hole recombination which contributed to an enhanced photocatalytic activity, when compared to the Degussa P25 photoactivity. The effect of silver nanoparticles and GO addition to TiO2 nanopowder was evaluated for photocatalysis activity. An improvement in the methylene blue and rhodamine B dyes photodegradation was observed for both anatase and rutile TiO2 nanocomposites. We noted that anatase TiO2 nanoparticles degraded 53% of rhodamine B, and when functionalized with GO, the photodegradation increased to 69%. Comparatively, the addition of silver nanoparticles to anatase TiO2 increased the dye degradation to 97% in 180 min. Hence, we revel that in the TiO2 nanocomposites, silver nanoparticles showed better interfacial charge transfer than GO, contributing more effectively to the dye photodegradation process.

Synthesis of Ag−/Graphene Aerogel Composite for Removal of Methyl Orange

“…Therewithal, its strong interaction with photons in the UV source, visible light, or natural sunlight leads to an energetic excitation, namely localized surface plasmon resonance (LSPR), on the surface of AgNPs. [14] The interaction of resonant light with AgNPs generates a strong electric field on the surface of the nanoparticles, which can induce photochemical transformations through local heating of the nanostructure. From the theoretical construction, the combination of three components including TiO 2 nanoparticles, AgNPs, and GA: the ATG nanocomposite is produced with an increased total number of active sites of the adsorption and photodegradation system.…”

Performance of TiO2-Based Tubular Membranes in the Photocatalytic Degradation of Organic Compounds

“…Noble metals, such as Ag and Au, are commonly used to enhance the photocatalytic performance of TiO 2 , as they act as an electron sink. The formation of Schottky junctions between semiconductors and noble metal nanoparticles increases the efficiency of charge carrier separation [17,18].…”

Solvothermal Synthesis, Structural Characterization and Optical Properties of Pr-Doped CeO2 and Their Degradation for Acid Orange 7

“…The greatest advantages of the photocatalytic process consist of not only the general mild reaction conditions, but also the possibility to abate refractory, toxic and difficult or non-biodegradable organic molecules [ 24 , 25 ]. Titanium dioxide (TiO 2 ) is the most studied and widely used photocatalyst in the removal of organic dyes because of its non-toxicity, low-cost and excellent photocatalytic properties [ 26 , 27 ]. CeO 2 , an N-type semiconductor, is one of the more active, versatile and inexpensive rare earth oxides [ 28 ], which should be an alternative candidate photocatalyst due to the readily available intrinsic oxygen vacancies in CeO 2 crystal.…”