Localized surface plasmon resonance for improving optical absorption in core-shell Ag@TiO2 nanoparticles

Abstract

Titanium dioxide (TiO 2 ) has attracted extensive attention in environmental and biomedical applications, owing to its excellent chemical and photochemical stabilities, non-toxicity, and high degradation capacity. However, the wide band gap and low quantum yield of TiO 2 limit its practical applications, and it is possible to improve the optical efficiency and sensitivity of TiO 2 in the visible spectrum. In this work, theoretical calculations based on optical absorption in core-shell structured Ag@TiO 2 nanoparticles (NPs) combined with the surface plasmon resonance property of the core and photoactivity of the shell were investigated as a function of incident light wavelengths in visible spectrum. Shifting of wavelength, at which light was absorbed and enhanced optical absorption activity of TiO 2 NPs due to localized surface plasmon resonance excitation were clearly observed at a level greatly exceeding the value calculated for pure TiO 2 NPs. The calculated results suggest that both the interparticle distance and the diameter of Ag core in the core-shell structure of Ag@TiO 2 NPs influence the tuning and the enhancement of optical absorption spectra. These findings of enhanced optical absorption could be utilized as basic knowledge to design and synthesize Ag@TiO 2 NPs for future environmental and biomedicine applications.

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