Prepared Three-Dimensional Flowerlike MoS2/Ag@rGO Nanocomposite as a Self-Cleaning SERS Substrate for the Trace Detection of 17β-Estradiol in Environmental Water

17β-E2 was the most active sterol estrogen and was widely used in animal husbandry for animal fattening and increasing milk production. Its abuse has resulted in residues in the environment. However, even very low concentrations could still enter the human body through the enrichment of the food chain and have adverse effects on the endocrine system. The SERS analysis method was employed in this work for the trace detection of 17β-E2 in environmental water. Cheap Ag NPs were selected as SERS sources. MoS2 provided a platform for the orderly arrangement of Ag NPs while making the material self-cleaning. rGO was coated in the outermost layer and had a protective effect on Ag NPs and could avoid oxidation during storage and use. At the same time, the target molecule could be adsorbed to reduce the distance between itself and Ag NPs, thus enhancing the SERS signal. The material had a high SERS enhancement factor (EF = 1.95 × 107), low detection limit (LOD = 5 × 10–12 M), good linear relationship (R2 = 0.994), good stability (RSD = 4.74%), and strong anti-interference ability. The recovery of 17β-E2 in farm wastewater samples was 100.15–108.00% and RSDs were 1.09–2.57%.