Structure and optical properties of (Alqx)/Al2O3 ethanol colloids

An investigation into the structure and chemical stability of green light emitting aluminum complexes of 8-hydroxyquinoline (Alqx)/Al2O3 colloids was performed. (Alqx)/Al2O3 ethanol colloid was characterized by the high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, thermogravimetric and simultaneous differential thermal analysis, and thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA/FTIR). The results show that the (Alqx)/Al2O3 nanoparticles are composed of an inner core of crystalline Al2O3 and an outer layer of 8-hydroxyquinoline (Q) coordinated to the surface aluminum ions of Al2O3 the nanoparticles. The luminescence intensity of the (Alqx)/Al2O3 ethanol colloids decreased upon the increasing aging time, and is accompanying by the presence of a brown material and a dark brown deposit produced in the colloids. The main component of the deposit was polystyrene. These findings can be explained by a process where Q coordinates to the surface ions of the Al2O3 particles, followed by degradation of the pyridine ring of 8- hydroquinonline, leading to the formation of polystyrene.