Versatile titanium dioxide nanoparticles prepared by surface-grown polymerization of polyethylenimine for photodegradation and catalytic CeC bond forming reactions

Abstract

Crystalline TiO2 anatase nanoparticles have been synthesized by a sol-gel procedure with a certain ratio of brookite phase due to low calcination temperature. TiO2 NPs have been successfully functionalized with hyperbranched polyethylenimine polymer (PEI) by the surface polymerization of aziridine or with N1-(3-trimethoxysilylpropyl)-diethylenetriamine (DT) by surface silanization to form catalyst with notable basic and photocatalytic properties. The TiO2 NPs have been characterized by X-ray diffraction (XRD), adsorption-desorption isotherms, fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance UV–vis spectroscopy (DRUV-vis), elemental analysis, thermogravimetric analysis, transmission electron microscopy (TEM), photoluminiscence spectroscopy (PL) and solid-state voltammetry. Functionalized TiO2 NPs have revealed to be efficient in the photodegradation of methylene blue in water and as basic heterogeneous catalysts carbon-carbon forming reactions as Knoevenagel condensation, multicomponent reactions and Biginelli reaction. PEI-TiO2 with mesoporous structure and narrow size pore distribution, fulfill the requirements imposed to an eco-friendly and cost-effective catalyst since it is easily synthesized and recyclable.