In situ regulation nanoarchitecture of Au nanoparticles/reduced graphene oxide colloid for sensitive and selective SERS detection of lead ions

In this work, the colloid of Au nanoparticles (AuNPs)/reduced graphene oxide (rGO) was synthesized by growth AuNPs on rGO via the reduction of HAuCl₄ on graphene oxide (GO) nanosheets. The nanoarchitecture of the colloid could be controllably regulated through in-situ Pb²⁺-enhanced gold leaching reaction, which made the colloid be a flexible surface-enhanced Raman scattering (SERS) platform for Pb²⁺ detection. Upon the addition of Pb²⁺, the Raman signal of graphene underwent significant descent due to the decrease of the amount of the "hot spots", which was originated from Pb²⁺-accelerated dissolution of AuNPs on the graphene surface in the present of thiosulfate (S₂O₃^2-). Based on the change of SERS signal through in situ regulation the nanoarchitecture of the colloid, a sensitive and selective strategy for Pb²⁺ measurement was developed with a linear range from 5nM to 4μM as well as a low detection limit of 1nM. Furthermore, the SERS-based method was applied for the determination of Pb²⁺ in water samples with satisfactory results.