Effect of Calcination Temperature on Phase, Morphology, and Optical Properties of TiO₂ Nanoparticles and Boron Nitride Decorated TiO₂ Nanotubes

In this study, boron nitride (BN) is synthesized via the hydrothermal technique and subsequently utilized to decorate TiO 2 nanotubes (BN-TNTs) by the same method. The synthesized materials are subjected to heat treatment at temperatures ranging from 600 °C to 1000 °C. Notably, while the literature extensively covers studies focusing on the effect of temperature on the physicochemical properties of TiO 2 nanoparticles (NPs), there is a scarcity of information regarding the same for the BN-TNTs composite. X-ray diffraction (XRD) patterns revealed a significant phase transition from anatase to rutile for BN-TNTs at 900 °C and 1000 °C. UV–Vis diffuse reflectance spectroscopy (UV-DRS) reveals that the band gap of TiO 2 at 1000 °C is 2.826 eV, while BN-TNTs at 1000 °C exhibit a band gap of 2.839 eV. Brunauer–Emmett–Teller (BET) analysis at different calcination temperatures is employed to evaluate the pore size, specific surface area (SSA), and pore volume of the synthesized materials. High resolution transmittance electron microscopy (HR-TEM) images show particle growth for TiO 2 NPs and a change in the morphology for BN-TNTs. Through thermogravimetric analysis (TGA) employing a modified Coast and Redfern model, it was determined that BN-TNTs exhibited a higher activation energy (15 205.69 J/mol) compared to TiO 2 NPs (10 003.26 J/mol), indicating a lower susceptibility to thermal degradation and a greater energy requirement for initiating chemical transformations. These findings are crucial for comprehending the thermal stability and energy storage capabilities of these composites, thereby facilitating optimization across a spectrum of applications including energy storage and thermal management.