Highly sensitive electroanalysis of Pb(II) in Chinese herbal medicine by the activated Co site and electron transfer medium S over Co9S8@MoS2 heterostructures

Designing a highly sensitive electrochemical sensing interface and elucidating the mechanism of enhanced electrochemical signals from the perspective of electronic structure are crucial for accurate detection of heavy metal ions (HIMIs). In this study, a composite transition metal sulfide Co 9 S 8 @MoS 2 heterostructure was developed for the high-sensitivity detection of Pb(II) in Chinese herbal medicine, which achieved a high sensitivity of 103.3 ± 0.5 μA μM −1 and a detection limit of 0.01 μM. Moreover, the fundamental reason for the excellent detection of Pb(II) was investigated by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). The results indicated that the recombination of the heterojunction not only catalyzes the activation of the Co site in Co 9 S 8 but also promotes S as a medium in the electron channel for increased charge transfer. In addition, the proposed method displayed anti-interference ability with outstanding stability and reproducibility in the presence of other HMIs. Importantly, the highly sensitive detection of Pb(II) has also been inherited in herbal Rehmannia glutinosa samples, demonstrating its potential for practical application in the detection of heavy metal ions in Chinese herbal medicine. This work provides essential theoretical guidance for constructing high-performance electrochemically sensitive interfaces from electronic structure-controlled sensing materials.