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

Uniform deposition of metal nanoparticles (NPs) on carbon-based substrates is of importance for practical applications as sensors, catalysts, devices, and so forth. Here, we report a one-step wet-chemistry approach that realizes the highly uniform decoration of gold NPs (Au NPs) onto carbon nanotube (CNT) sheets. We first use plasma treatment to 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 interstitial space for gold deposition, but also attracts the gold cluster nucleation due to molecule interactions. The reproducibility of surface-enhanced Raman scattering (SERS) signals from this well-engineered CNT/Au NPs substrate is significantly enhanced, as the relative standard deviation from 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 on Au NPs/CNT hybrid, which can effectively detect the analyte Rhodamine 6G (R6G) at a concentration as low as 1 × 10^-8 M.