A facile and green one-step synthesis of Ag/reduced graphene oxide and its application in catalysts and SERS

Herein, we present a facile one-step approach for synthesizing Ag/reduced graphene oxide (Ag-rGO) through synchronous reduction and <i>in situ</i> coagulation of graphene oxide (GO) and silver nitrate (AgNO₃) under a nitrogen atmosphere. In this process, GO serves as the carrier and template, AgNO₃ as the precursor, and rutin functions both as the reducing and stabilizing agent. The Ag-rGO nanocomposite is synthesized using an eco-friendly method, where spherical silver nanoparticles are randomly dispersed on the surface of reduced graphene oxide (rGO). This nanocomposite exhibits excellent catalytic activity for degrading methylene blue (MB) and demonstrates good surface-enhanced Raman scattering (SERS) activity as a SERS substrate. It was found that 3 mg Ag-rGO attained a decolorization rate of 96% within merely 9 minutes, with a corresponding reaction rate constant (<i>k</i>) of 0.362 min^-1. SERS detection of R6G also exhibited good performance in terms of detection limits in the order of 10^-7 M, an enhancement factor of 3.03 × 10⁵, and high reproducibility (the maximum intensity deviation < 7.01%). The excellent performance can be attributed to the decreased size of Ag on the nanocomposite and the larger specific surface area achieved through the <i>in situ</i> synchronous reduction and coagulation method. Additionally, the <i>in situ</i> enrichment effect and superior electron transfer efficiency further enhance the catalytic performance of the nanocomposite, and the synergistic effect of chemical enhancement and electromagnetic enhancement contribute to the good Raman enhancement effect. The effects of reaction parameters such as time and varying reactant ratios on the catalytic and SERS activities of the nanocomposite were also investigated. These findings indicate the potential ability of the Ag-rGO for practical environmental monitoring and treatment applications.