Highly Uniform Fabrication of Gold Nanoparticles on Carbon Nanotube Sheets for Sensors Based on Surface-Enhanced Raman Spectroscopy with Improved Reproducibility

Uniformdeposition of metal nanoparticles (NPs) on carbon-basedsubstrates is of importance for practical applications as sensors,catalysts, devices, and so forth. Here, we report a one-step wet-chemistryapproach that realizes the highly uniform decoration of gold NPs (AuNPs) onto carbon nanotube (CNT) sheets. We first use plasma treatmentto make the CNT bundles separated, namely, applying the "debundling"effect onto the film. We also reveal that dimethyl sulfoxide (DMSO)not only promotes the CNT debundling, providing more interstitialspace for gold deposition, but also attracts the gold cluster nucleationdue to molecule interactions. The reproducibility of surface-enhancedRaman scattering (SERS) signals from this well-engineered CNT/Au NPssubstrate is significantly enhanced, as the relative standard deviationfrom G and D peaks are decreased from 18.8 and 21.3% to 5.6 and 6.2%,respectively. We have fabricated a flexible SERS substrate based onAu NPs/CNT hybrid, which can effectively detect the analyte Rhodamine6G (R6G) at a concentration as low as 1 x 10(-8) M.