Three-dimensional multi-walled carbon nanotube arrays coated by gold-sol as a surface-enhanced Raman scattering substrate

We demonstrated a three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrate consisting of large area carbon nanotube (CNT) arrays coated by gold-sol nanoparticles. A low-cost, simple process is used to prepare Au-decorated 3D CNT arrays. The SERS enhancement from the 3D CNT arrays, and two-dimensional (2D) CNT films substrates coated by different size gold-sol nanoparticles, was experimentally verified with Rhodamine 6G as the probe analyte. The experiments showed that the 3D CNT arrays substrate has a higher Raman enhancement compared with 2D CNT arrays substrate and planar glass substrate, due to the large specific surface area of CNT arrays and more gold nanoparticles on the CNT arrays sidewalls, which contribute the electromagnetic field and Raman intensity. Meanwhile, the 3D structure could enhance the excitation light trapping in CNT arrays, consequently increasing the light interaction with Au nanoparticles.