Ag/GO/TiO2nanocomposites: the role of the interfacial charge transfer for application in photocatalysis

Gabriella Correia de Almeida; Nelcy Della Santina Mohallem; Marcelo Machado Viana

doi:10.1088/1361-6528/ac2f24

Ag/GO/TiO₂nanocomposites: the role of the interfacial charge transfer for application in photocatalysis

Nanotechnology. 2021 Oct 29;33(3). doi: 10.1088/1361-6528/ac2f24.

Authors

Gabriella Correia de Almeida¹, Nelcy Della Santina Mohallem¹, Marcelo Machado Viana¹

Affiliation

¹ Departamento de Química, Universidade Federal de Minas Gerais, ZIP 31270-901, Belo Horizonte, MG, Brazil.

PMID: 34638115
DOI: 10.1088/1361-6528/ac2f24

Abstract

TiO₂semiconductor 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 TiO₂and 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 TiO₂nanopowder was evaluated for photocatalysis activity. An improvement in the methylene blue and rhodamine B dyes photodegradation was observed for both anatase and rutile TiO₂nanocomposites. We noted that anatase TiO₂nanoparticles degraded 53% of rhodamine B, and when functionalized with GO, the photodegradation increased to 69%. Comparatively, the addition of silver nanoparticles to anatase TiO₂increased the dye degradation to 97% in 180 min. Hence, we revel that in the TiO₂nanocomposites, silver nanoparticles showed better interfacial charge transfer than GO, contributing more effectively to the dye photodegradation process.

Keywords: graphene oxide; microwave; photocatalysis; silver nanoparticles; titanium dioxide.