Superparamagnetic titanate nanocomposites obtained from a polymorphic mixture of titanium dioxide

Abstract

The n-type titanate heterojunction with p-type transition metal oxides reduces the recombination effect (e−/h+) and improves the magnetic, electronic, and luminescent properties. Based on these related properties, the synthesis of nanocomposite sodium-cobalt titanate nanotube and iron oxide (Co-NaTiNT@FeO) was performed using titanium dioxide (polymorphic mixture: brookite, anatase and rutile), cobalt nitrate hexahydrate and iron oxide (FeO). The synthesized materials were characterised by X-ray diffraction (XRD), Raman and infrared (IR) spectroscopies, thermogravimetry and differential (TG-dTG), transmission electron microscopy (TEM) and scanning (SEM), X-ray photoelectron spectroscopy (XPS), adsorption/desorption of N2 by Brunauer-Emmett-Teller (BET) method, Ultraviolet–Visible (UV–Vis) by diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and vibrating sample magnetometer (VSM). The results revealed the presence of Co2+ ions in the lamellar region of the nanotubes, in addition to verifying that there was no collapse of the nanotubes before and after the anchoring of the FeO nanoparticles. Using the XPS technique, the presence of 2.49 wt% of Fe (2p), as well as 1.55 wt% of Co (2p), was identified; these elements favoured the band gap reduction from 3.61 to 2.66 eV compared to sodium titanate nanotube (NaTiNT); in addition, they favoured the emergence of emissions associated with the red, yellow, and orange colours, described through PL. The surface area of the composite changed from 197.00 to 210.46 m2 g−1, possibly due to the homogeneous presence of anchored superparamagnetic FeO nanoparticles. Finally, the results were consistent with the proposal for the synthesis of Co-NaTiNT@FeO, which had improvements in its properties, especially its magnetic properties.