Visible-light-driven charge transfer to significantly improve surface-enhanced Raman scattering (SERS) activity of self-cleaning TiO2/Au nanowire arrays as highly sensitive and recyclable SERS sensor

2019 
Abstract We apply a facile photoreduction deposition strategy to grow Au nanoparticles (NPs) on the surfaces of TiO 2 nanowire arrays (TiO 2 /Au NWAs) as a Raman sensitive substrate. The fabricated TiO 2 /Au NWAs can be used as a highly sensitive and recyclable SERS sensor for detecting the rhodamine 6 G (R6 G) molecules with a concentration as low as 10 −9 M. Moreover, when irradiated with UV light, the SERS sensor with high sensitivity can be fully reproduced due to the superior self-cleaning capability of the substrate. By a comparative study on the SERS activities of R6 G molecules over the substrates of pure TiO 2 NWAs, pure Au NPs and TiO 2 /Au NWAs, as well as the photoresponse performance of pure TiO 2 and TiO 2 /Au NWAs under visible light illumination, we provide an illuminating insight into enhanced mechanism of SERS activity for TiO 2 /Au NWAs. The photoresponse performances and SERS activities provide experimental evidence that enhanced SERS activity of TiO 2 /Au NWAs is ascribed to the efficient charge transfer among Au, TiO 2 and R6 G. This work throws a new light on enhanced mechanism for SERS activity of semiconductor/noble-metal substrates, which are expected to find potential applications to fabricate highly sensitive SERS sensors for the detection of analytes.
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