Graphene oxide@silver nanoparticles with oxidase-like activity and Raman enhancement ability for colorimetric-SERS detection of H2S.

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.