The influences of graphene oxide (GO) and plasmonic Ag nanoparticles modification on the SERS sensing performance of TiO2 nanosheet arrays

A sensitive solid semiconductor-based surface-enhanced Raman spectroscopy (SERS) substrate can realize recyclable and portable detection of organic pollutants. In this paper, TiO2 nanosheets (NSs) on FTO glass substrate were synthesized by a simple and controllable hydrothermal method, followed by decoration of plasmonic Ag nanoparticles (AgNPs), and further deposition of graphene oxide (GO). The GO and AgNPs co-modified TiO2 substrate showed improved signal reproducibility, longer-term stability, and higher detection sensitivity than that of TiO2 counterparts. Note that, the optimized TiO2-Ag-GO substrate can also be utilized to discriminate multiple organic pollutants with a portable Raman instrument. The limit of detection (LOD) for crystal violet (CV), rhodamine 6 G (R6G) and malachite green (MG) was 10−9 M, 10−8 M, and 10−7 M, respectively. Moreover, the solid substrate was applied to discern low concentrations of CV residue (10−8 M) on crayfish’s shell and thiram residue (10−6 M) on grape skin. As a proof of concept, multiplex detections were also demonstrated. More significantly, the better photocatalytic degradation performance of the TiO2-Ag-GO makes the solid substrate reuse for 10 cycles. The solid SERS substrate may have great potential for practical applications and resource-confined detections.