Silver-modified titania with enhanced photocatalytic and antimicrobial properties under UV and visible light irradiation

• Ag@TiO2-active decomposition of methanol, acetic acid, 2-propanol and Escherichia coli.
• Possible electron storage in Ag nanoparticles hinders charge recombination.
• Plasmon resonance is responsible for photocatalytic activity under visible light.
• Mineralization of bacteria cells was achieved under UV and visible light.
• Mechanism study by action spectra and time-resolved microwave conductivity methods.

Commercial titania photocatalysts were modified with 2 wt% of silver by photodeposition. The properties of the samples were characterized by DRS, XPS, XRD, FE-SEM and STEM. The modified samples exhibited activity under visible light and enhanced activity under UV irradiation for 2-propanol and acetic acid oxidation, respectively. The time-resolved microwave conductivity (TRMC) analysis indicated that enhanced activity (2.5–8-fold enhancement depending on titania) under UV irradiation was caused by an electron storage in metallic nanoparticles (NPs), and therefore decreasing the recombination between charge carriers. The action spectrum (AS) analysis proved that localized surface plasmon resonance (LSPR) of silver NPs induced the photocatalytic activity under visible light irradiation. The increase of antimicrobial properties under visible light irradiation indicated that not only intrinsic properties of silver in the dark, but also plasmonic properties of Ag@TiO2 were responsible for overall bacteria killing. The evolution of carbon dioxide under both irradiation ranges indicated mineralization of bacteria cells, and therefore possible application of silver-modified titania for decomposition of chemical and biological pollutants.

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