Graphene oxide@silver nanoparticles with oxidase-like activity and Raman enhancement ability for colorimetric-SERS...

A hybrid material GO@Ag composed of graphene oxide (GO) decorated with silver nanoparticles (AgNPs) was prepared for sensitive detection of hydrogen sulfide (H₂S), a food spoilage indicator and a toxic gas. The GO@Ag nanocomposite demonstrated excellent oxidase-like activity and Raman signal enhancement capability, which can effectively catalyze colorless 3,3',5,5'-tetramethylbenzidine (TMB) to produce oxidized TMB (ox-TMB) with blue color and strong surface-enhanced Raman scattering (SERS) signals. The presence of H₂S reacts with AgNPs on the GO surface to form Ag₂S, which inhibits the nanozyme activity and SERS enhancement activity of the GO@Ag, resulting in decreased absorbance value and SERS signal, thereby achieving colorimetric and SERS dual-mode detection of H₂S. The method exhibits a wide linear range of 10 nM ~ 50 μM (colorimetry) and 5 nM ~ 50 μM (SERS) and low detection limits of 9 nM (colorimetry) and 0.9 nM (SERS) with simple operation, good selectivity, and high reproducibility. Furthermore, the composite material has been successfully applied to the detection of H₂S in actual fish samples, providing a new technical means for gas sensing in food safety monitoring.