Green synthesized Ag decorated CeO₂ nanoparticles: Efficient photocatalysts and potential antibacterial agents

Implication of natural resources for manufacturing of nanoparticles is sustainable, economical and contaminant free approach towards ecological and medical applications. Herein, CeO₂ and Ag/CeO₂ nanoparticles are green synthesized from Morinda tinctoria plant extract. The phase structure, surface morphology, optical identity, Ce(III) and Ce(IV) valency of the synthesized CeO₂ and Ag/CeO₂ nanoparticles are explored. The X-ray diffraction analysis indicated the formation of cubic phase CeO₂ and cubic silver decorated CeO₂ nanoparticles. Fourier transform infrared (FTIR) spectroscopy revealed the metal decoration of CeO₂ nanoparticles, metal-oxygen stretching, indicating the plant molecules reduction and stabilization. UV-visible spectroscopy shown the decreased band gap owing to silver modification. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs displayed spherical morphology of the nanoparticles. Elemental composition and sample purity is assessed by energy dispersive spectroscopy (EDS). Double oxidation of Ce, double splitting energy of Ag and lattice oxygen are observed from X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of Ag/CeO₂ exposed the enhanced photocatalytic activity up to 94% where CeO₂ nanoparticles gave 60% degradation of bromophenol blue (BB). The plasmonic decoration of silver on the ceria surface induced the charge separations and free radical reactions. Moreover, Ag/CeO₂ nanoparticles are seen as superior antibacterial agents than CeO₂ towards both E.coli and S.aureus. Hence, the silver decorated metal oxide photocatalyst successfully degraded the BB dye and inactivated the bacterial strains. This report established a future research in green synthesis of multipurpose metal nanoparticles.