Periodic Arrays of 3D AuNP-Capped VO_2 Shells and Their Temperature-Tunable SERS Performance

摘要

In this work, periodic arrays of 3D composite structures consisting of gold nanoparticle (AuNP) capped VO2 shells on self-assembled highly-ordered SiO2 microspheres have been designed and fabricated, and their temperature-tunable surface-enhanced Raman scattering (SERS) performance is investigated. The results show that the SERS intensity enhancement factor (EF) for R6G molecules adsorbed on the AuNP-capped VO2 shells increases from 8.3 x 10(5) to 3.9 x 10(6) when triggering the semiconductor-to-metal phase transition of VO2 by temperature rise, which strengthens the plasmonic coupling between the AuNPs and VO2 shells and consequently leads to a larger electric near-field enhancement at the gaps between neighboring AuNPs. Such periodic arrays of AuNP-capped VO2 shells with tunable plasmonic coupling can provide great opportunities for various optical applications, such as quantitative SERS detection of analytes, photothermal nano-regulators, and biosensing in general.