Synthesis and study of the structure and properties of photocatalytic nanocomposites of the Cu/ZnO-ZnCr2O4 system

Currently, the development of new nanocomposite materials with improved photocatalytic and antibacterial properties is a topical task for environmentally friendly technologies for water and air purification. This paper presents the results of a study of ZnO-ZnCr 2 O 4 and Cu/ZnO-ZnCr 2 O 4 powder nanocomposites obtained by the polymer-salt method. For the synthesis of nanocomposites, zinc and chromium nitrate solutions with the addition of polyvinylpyrrolidone as a soluble organic polymer were used. The structure and morphology of the nanocomposites were studied by XRD analysis and electron microscopy, optical and luminescent properties using spectroscopic methods. As a result of heat treatment at 550 °С, dispersed powders of nanocomposites were obtained, consisting of particles several micrometers in size, including hexagonal ZnO nanocrystals with an average size about16 nm and ZnCr 2 O 4 spinel crystals. In the luminescence spectrum of the Cu/ZnO-ZnCr 2 O 4 composite in the visible region, fluorescence bands are observed characteristic of ZnCr 2 O 4 crystals and structural defects of ZnO crystals. It was found that the intensity of singlet oxygen photogeneration by the Cu/ZnO-ZnCr 2 O 4 nanocomposite linearly depends on the power density of the exciting radiation (the wavelength is 405 nm). Antibacterial activity of the Cu/ZnO-ZnCr 2 O 4 nanocomposite against Staphylococcus aureus ATCC 209P bacteria was also revealed. The obtained nanocomposite powders can be used in water and air purification and disinfection systems.