@conference{
author = "Simović, Bojana and Dapčević, Aleksandra and Zdravkovic, Jelena and Krstić, Jugoslav and Branković, Goran",
year = "2018",
abstract = "Regarding their extraordinary properties, such as biological and chemical sta-bility, photocatalytic activity, cost-effectiveness, the titanium-based nanoma-terials are the subject of an intense research. Although titania is well knownas a photocatalyst, the titanates are promising candidates for the wide rangeof applications including ion exchange, high adsorption capacity toward or-ganic molecules and radioactive toxic metal ions[2], in photovoltaics, H- andLi-storage, gas sensors, etc. The hydrothermal process became a very import-ant way to obtain these materials in nanostructural form since the discovery ofanatase-based alkaline hydrothermal treatment reported by Kasuga et al. [1].In this work, nine products were obtained by modifying the experimental conditions(6, 12 and 18 h at 110, 135 and 160 °C) of hydrothermal treatment of starting nano-anatase in less alkaline medium (5 mol dm–3 NaOH solution) than usual. Specimensare labeled as TT–t, where T is temperature of the treatment and t is duration of thetreatment. The step-by-step optimization of this simple and costless procedure wasnecessary in order to obtain a pure titanate phase and to finally distinguish the ti-tanates from titania in terms of structure and microstructure. The nanocrystallinesamples were characterized by HRTEM/SAED, XRPD, EDS, TG, UV-VIS and BETtechniques.According to XRPD and HRTEM, the complete conversion of anatase to puretitanate phase was achieved after energetically the most intensive treatment, i.e.18 h at 160 °C. Among other products, a certain amount of anatase remained,with its decreasing content as the temperature and time of hydrothermal treatmentincreases. This increment significantly improves the solubility of TiO2 promoting thechanges in morphology from the approximately spherical anatase nanoparticles intoelongated titanate nanosheets (Fig. 1). Based on EDS and TG, the Na0.4H1.6Ti2O5·H2Oformula could be assigned to T160_18. The HRTEM/SAED revealed the shortening ofinterplanar distances along aaxis because of the dehydratation due to the high vacuumof the TEM chamber and high energy of the electron beam irradiation confirming thelayered structure of Na0.4H1.6Ti2O5·H2O (Fig. 2). Because of the poor characterizationof titanate nanosheets found in literature, the optical and textural properties ofproducts were also investigated. A blue shift toward lower wavelength is observedwith the temperature increasing being the most pronounced for the T160_18 (Fig. 3).This is the consequence of full transformation of TiO2 into Na0.4H1.6Ti2O5·H2O. Forthe same reason, the values of specific surface areas decreased with the temperatureincreasing.As shown in this work, the structure, morphology and texture of samples stronglydepend of the conditions of hydrothermal treatment. The production of single phasetitanate and its detailed microscopic characterization finally allowed the clarificationof long-standing confusion between titania and titanates.References:[1] T Kasuga et al, Langmuir 14 (1998), p. 3160.[2] Y Zhang et al, RSC Advances 5 (2015), p. 79479.[3] The authors acknowledge funding from the Ministry of Education, Science andTechnological Development of the Republic of Serbia, Grant Numbers III45007and III45019. The support of the bilateral cooperation with Slovenia is alsogratefully acknowledged (Project No. 451-03-3095/2014-09/32).",
publisher = "Serbian Academy of Sciences and Arts, Belgrade",
journal = "First International Conference of electron microscopy of nanostructures (ELMINA 2018)",
title = "From Titania to Titanates: Phase and Morphological Transition",
pages = "148-150",
url = "https://hdl.handle.net/21.15107/rcub_cer_6764"
}
