Undoped and doped titania-based hollow spheres for photocatalysis

The present work reports the investigation of the fabrication of undoped and doped titania hollow spheres, implicating a hard template method followed by a calcination process, and the strategies to enhance the photocatalytic degradation of a drug by using different quantities of dopants, in particular nitrogen and copper. Polymethyl methacrylate (PMMA) nanoparticles were used as a template and were prepared by polymerisation. The second step involved the coating of the sacrificial template using a titanium precursor, titanium(IV)butoxide (TBOT), to obtain a TiO2@PMMA core-shell system. Undoped titania hollow spheres were prepared by sol-gel method mixing PMMA nanospheres and titanium precursor in absolute ethanol, under alkaline condition. Different quantities (from 0.3 to 3 at%) of nitrogen and copper were added to the solution, to obtain doped-titania hollow spheres. In addition, co-doping in different Cu/N atomic percentage ratios was investigated. The calcination process allowed the removal of PMMA-templates in order to obtain titania hollow spheres (THSs) undoped, doped and co-doped. The synthesized products were characterized by X-ray diffraction (XRD), diffuse reflectance UV-Vis-NIR, Scanning Electron Microscope (SEM) and Energy dispersive X-Ray (EDX). In addition, all the THSs were tested for photodegradation of a target drug (Metronidazole, MDZ) under UV and solar simulator light irradiation to evaluate the photoactivity and establish the best performing system.