Electrochemical preparation of polypyrrole-molybdenum disulfide-graphene nanocomposite coating for the determination of phenols

In this work, a nanocomposite of molybdenum disulfide (MoS₂) and graphene (r-GO) was synthesized using hydrothermal method, and was subsequently employed as a dopant to fabricate a hybrid coating of polypyrrole (PPy)-r-GO-MoS₂ via cyclic voltammetry (CV). The resulting coating was applied to extract five phenolic compounds, and combined with gas chromatography-mass spectrometry (GC–MS) to establish an analytical method for the determination of 3‑chloro-4-fluorophenol, 2‑chloro-4-methoxyphenol, 2,6-dimethoxyphenol, 2,4,6-trichlorophenol, and 2,6-dichloro-4-nitrophenol in environmental samples. The results indicated that PPy-MoS₂-r-GO coating exhibited superior extraction efficiency in comparison with to PPy coating. To optimize testing conditions, MoS₂-r-GO concentration for the electrochemical preparation of the coating, extraction conditions, including time, temperature, and stirring speed, were also investigated. Consequently, the analytical method exhibited an excellent linear response, with a correlation coefficient ranging from 0.9950 to 0.9980 for the five phenolic compounds in the range of 0.01 μg L⁻¹ to 50 μg L⁻¹. The detection limits were 0.00550 μg L⁻¹ - 0.00850 μg L⁻¹. This method was employed to detect phenol in real samples, yielding recoveries ranging from 89.60 % to 103.30 %, thereby confirming its practical applicability.