Metal-free and flexible surface-enhanced Raman scattering substrate based on oxidized carbon cloth

Flexible surface-enhanced Raman scattering (SERS) substrates show great potential application in environmental, biological and technological sensors. However, most of flexible SERS substrates are designed based on depositing or embedding metal (Ag, Au, Cu) particles on or into polymer supports or woven fibers without SERS activity, which suffer from complex manipulation processes and high cost. In this work, oxidized carbon cloth fabricated by chemical oxidation of commercial carbon cloth used as a metal-free and highly flexible SERS substrate with detection of limit for Rhodamine 6G down to below 10(-8) M is reported. The SERS sensitivity of oxidized carbon cloth is improved by more than 3 order magnitude than untreated carbon cloth. By combining experimental analyses and theoretical calculations, it is proved that rich oxygen-containing functional groups on carbon cloth surface introduced by chemical oxidation leads to enhanced charge transfer (chemical enhancement) between oxidized carbon cloth and adsorbed molecules, which is responsible for the improved SERS performance. This work may pave the way for metal-free and flexible SERS substrate design and provides valuable insights for carbon-based SERS substrate. (C) 2021 Elsevier Ltd. All rights reserved.