Reduced graphene oxide-wrapped silver nanoparticles for applications in ultrasensitive colorimetric detection of Cr(vi) ions and the carbaryl pesticide

Reduced graphene oxide-wrapped silver nanoparticles (Ag@rGO) were synthesized by a simple photochemical process with the GO nanosheets as both a stabilizing and reducing agent. The synthesized Ag@rGO nanohybrids were used as a localized surface plasmon resonance (LSPR) colorimetric sensor for the detection of chromium(vi) and carbaryl. For chromium(vi), the result showed a color change from yellow to colorless and linear-dependence of the absorption intensity on the concentration of Cr(vi) in the range 0.1-25 mu M. For carbaryl, the calibration curve presented a high level of linearity in the range of 0.1-50 mu M corresponding to color changes from yellow to purple. The limits of detection (LODs) for Cr(vi) and carbaryl were found to be 31 nM and 42 nM, respectively. The novel Ag@rGO nanohybrids will become an excellent platform for colorimetric probes in the detection of Cr(vi) ions and carbaryl or other heavy metal ions/pesticides.