pH-dependent surface-enhanced Raman scattering of aromatic molecules on graphene oxide

Graphene has become an ideal substrate for surface-enhanced Raman scattering (SERS) to study the chemical enhancement mechanism. In comparison with mechanically exfoliated graphene, graphene oxide (GO) has been found to be a better substrate due to its highly negatively charged oxygen functional groups. In this work, the pH-dependent SERS effect of aromatic molecules on GO are investigated. The results demonstrate that the Raman enhancement of dyes deposited on GO performs differently over a wide range of pH values (2 to 10). Adsorption experiments show that the pH-dependent SERS effect is closely related to the adsorption of aromatic molecules on GO, which is dominated by the electrostatic interaction. Thus, the influence of pH in GO-mediated SERS should be carefully considered, especially in its biomedical application. Copyright (C) 2012 John Wiley & Sons, Ltd.