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

Titanium dioxide (TiO2) 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 TiO2 limit its practical applications, and it is possible to improve the optical efficiency and sensitivity of TiO2 in the visible spectrum. In this work, theoretical calculations based on optical absorption in core-shell structured Ag@TiO2 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 TiO2 NPs due to localized surface plasmon resonance excitation were clearly observed at a level greatly exceeding the value calculated for pure TiO2 NPs. The calculated results suggest that both the interparticle distance and the diameter of Ag core in the core-shell structure of Ag@TiO2 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@TiO2 NPs for future environmental and biomedicine applications.