Mesocrystalline anatase nanoparticles synthesized using a simple hydrothermal approach with enhanced light harvesting for gas-phase reaction.

Abstract

Mesocrystalline TiO2 nanoparticles were synthesized using a hydrothermal approach. A simple two-step procedure at low temperature (<140 °C) allowed the nucleation of primary particles sized 2-4 nm and their subsequent assembly as almost spherical aggregates sized ≈20 nm. X-ray powder diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) studies, and HRTEM studies confirmed anatase as the unique TiO2 crystalline phase. The mesocrystalline structure of the anatase aggregates was clearly evidenced by HRTEM and SAED results. The mesocrystalline nanopowders exhibit a mesoporous structure with a surface area and pore volume of 63.5 m2 g-1 and 0.22 cm3 g-1, respectively. Ultraviolet (UV) and visible light (Vis) absorption ability were recorded. The combined high effectiveness and selectivity for the NOx abatement of the new mesocrystalline photocatalyst are reported. It is worth remarking that the maximised selectivity values reached for the NOx process are reported for the first time and could be associated with the mesoporous nature of the anatase photocatalyst.