The Preparation of Au@TiO Yolk-Shell Nanostructure and its Applications for Degradation and Detection of Methylene Blue.

This paper reports the synthesis of a new type of Au@TiO yolk-shell nanostructures by integrating ion sputtering method with atomic layer deposition (ALD) technique and its applications as visible light-driven photocatalyst and surface-enhanced Raman spectroscopy (SERS) substrate. Both the size and amount of gold nanoparticles confined in TiO nanotubes could be facilely controlled via properly adjusting the sputtering time. The unique structure and morphology of the resulting Au@TiO samples were investigated by using various spectroscopic and microscopic techniques in detail. It is found that all tested samples can absorb visible light with a maximum absorption at localized surface plasmon resonance (LSPR) wavelengths (550-590 nm) which are determined by the size of gold nanoparticles. The Au@TiO yolk-shell composites were used as the photocatalyst for the degradation of methylene blue (MB). As compared with pure TiO nanotubes, Au@TiO composites exhibit improved photocatalytic properties towards the degradation of MB. The SERS effect of Au@TiO yolk-shell composites was also performed to investigate the detection sensitivity of MB.