ZnO/Ag hybrid nanocubes in alginate biopolymer: Synthesis and properties

•ZnO nanocubes were synthesized in the presence of alginate biopolymer.•The nanocubes were used for the preparation of ZnO/Ag heterostructures.•Spherical silver nanoparticles were formed on the vertices of ZnO nanocubes.•ZnO/Ag heterostructures showed strong photocatalytic and antimicrobial activity.

A procedure for the preparation of ZnO nanocubes in an alginate biopolymer was introduced. The obtained nanocubes were used for the preparation of ZnO/Ag heterostructures. High resolution scanning electron microscopy showed that reduction of silver salts in the presence of nanocubes results in the formation of spherical silver nanoparticles at their edges and vertices. UV–vis and photoluminescence spectroscopy revealed that alginate-ZnO/Ag nanostructures exhibit different optical properties compared to the starting alginate-ZnO system. The surface plasmon resonance peak of the silver nanoparticles dominates the absorption spectra of the ZnO/Ag hybrid particles, while at the same time the Ag nanoparticles quench the ZnO emission. The photocatalytic activity of the ZnO/Ag heterostructure was faster than that of the pure ZnO and further improved with increasing the concentration of silver. Both the alginate-ZnO and alginate-ZnO/Ag nanocomposites showed strong antimicrobial activities against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria.

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