Ru dye functionalized Au-SiO2@TiO2 and Au/Pt-SiO2@TiO2 nanoassemblies for surface-plasmon-induced visible light photocatalysis.

The most commonly used material in photocatalysis is TiO2. Since TiO2 absorbs only UV-light, photosensitizers are used to extend these catalysts' absorption properties into the Vis/NIR spectral range. In this work we merge the commonly used approach of dye sensitization with the only recently developed approach of functionalizing the catalyst with plasmonically active metal nanoparticles in order to achieve synergistic effects between these two types of visible light sensitization. To this end SiO2@TiO2 nanostructures are functionalized with gold nanoparticles or a combination of gold/platinum nanoparticles loaded with Ru dyes and thoroughly characterized by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) imaging as well as energy dispersive X-ray spectroscopy (EDX), UV/VIS and surface enhanced resonance Raman scattering (SERRS) spectroscopy. The photocatalytic performance is tested by applying the benchmark experiment of methylene blue degradation. Spectroscopic investigations and electron microscopy proof the successful synthesis of the envisioned structure. The photocatalytic activity of the nanostructures shows up to 52% higher first order rate constants compared to the corresponding nanostructures without further dye functionalization.