Herbal synthesis of integrated binary-semiconductor nanocomposites of silver doped CuO with ZnO/SnO2 for antibacterial activities and photocatalytic degradation of organic dyes.

Sida rhombifolia leaf extract was used to synthesize heterostructured nanocomposites Ag@CuO/ZnO and Ag@CuO/SnO2 by sol–gel combustion method followed by calcination. Through this ecofriendly approach, we could minimize the utilization of toxic chemicals as the bioactive components present in the plant extract act as capping and complexing agents. XRD studies indicated the formation of various crystalline phases of the congeners of the heterostructured nanocomposites. FESEM studies revealed irregular aggregates for AZC of particle size between 100 and 500 nm whereas uniformly arranged distorted spheres for ASC. The UV-DRS spectra helped to assess the reduced band gap energy from tau plot. The PL emission peaks of ZnO and SnO2 point towards the crystal defects in their lattices. The as-prepared ternary nanocomposites have resistivity to the growth of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeroginosa, Streptococcus mutans and Staphylococcus aureus with greater inhibition zones which showed their superior antibacterial activity. They are proved to be excellent photocatalysts for the degradation of hazardous organic dyes into harmless products and reduction of aromatic compounds into useful chemicals. Thus, the facile, low-cost and environmentally sustainable green synthesis provides Ag@CuO/ZnO and Ag@CuO/SnO2 nanocomposites with multifunctional efficacy. [ABSTRACT FROM AUTHOR]