Solvent effect on the structure and photocatalytic behavior of TiO 2 -RGO nanocomposites
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Solvent effect on the structure and photocatalytic behavior of TiO2-RGO nanocomposites Bruno S. Gonçalves1,a), Lucas M.C. Silva1, Tarcizo C.C. de Souza2, Vinícius G. de Castro2, Glaura G. Silva3, Bruno C. Silva4, Klaus Krambrock4, Renata B. Soares5, Vanessa F.C. Lins5, Manuel Houmard6,b), Eduardo H.M. Nunes1,c) 1
Departamento de Engenharia Metalúrgica e de Materiais, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil Centro de Tecnologia em Nanomateriais e Grafeno (CTNano), Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil 3 Centro de Tecnologia em Nanomateriais e Grafeno (CTNano), Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil; and Departamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil 4 Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil 5 Departamento de Engenharia Química, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil 6 Departamento de Engenharia de Materiais e Construção, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901, Brasil a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] c) e-mail: [email protected] 2
Received: 15 May 2019; accepted: 29 October 2019
There is no agreement regarding which solvent is more suitable to obtain sol–gel–derived titania (TiO2) samples with an enhanced photocatalytic behavior. Furthermore, the solvent effect on the preparation of TiO2-RGO (reduced graphene oxide) nanocomposites has not been published yet and could be an attractive experimental strategy to modulate structure and properties. On the basis of these observations, TiO2-RGO nanocomposites were fabricated in this study. It was evaluated for the influence of using either isopropyl (IsoprOH) or ethyl (EtOH) alcohol on the textural and photocatalytic properties of the prepared materials. The use of IsoprOH led to samples with smaller crystallite size, narrower apparent band gap, smaller isoelectric point, larger adsorption capacity, and higher photocatalytic activity. In addition, the incorporation of RGO into TiO2 greatly improved the adsorption capacity and photocatalytic activity of the latter. However, the optimal loading of RGO to prepare composites with enhanced photocatalytic activities was 1 wt%. This finding can be related to the stacking of RGO sheets when concentrations above 1 wt% are used, which could prevent UV light to reach the TiO2 particles and also decrease the photocatalytic capacity of the composites. Moreover, materials with RGO concentration above 1 wt% could exhibit a highly negatively charged surface, which may decrease the separation of the generated electron–hole pairs and lead to faster recombination rates of charge carriers.
Introduction Titanium dioxide (TiO2–titania) is one of the most used semiconductors in the photocatalysis field [1, 2, 3, 4, 5, 6, 7]. Besides exhibiting versatile preparation methods, titania also
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