Electrochemical Detection Of Pb(Ⅱ) Based On Bimetallic Sulphide Nanomaterials

With the development of human society in recent years,the problem of heavy metal pollution caused by human activities has become increasingly serious.Chinese herbal medicine is the main means and an important part of the treatment of various diseases in Chinese medicine,and is widely used to treat various diseases.However,heavy metals contaminated soil will be enriched in Chinese herbal medicine with the cycle of nature,and finally enter the human body with people’s intake.Therefore,the detection of Pb（II）in herbal medicines has become a key to prevent lead poisoning in humans due to the use of herbal medicines.Electrochemical detection methods have gained widespread interest in the field detection of heavy metals due to the simplicity and portability of the detection instrument,the high sensitivity of the results and the low detection limits.The construction of sensitive interfaces is an extremely important aspect in the electrochemical detection of heavy metals,where nanomaterials have excellent physicochemical properties such as large specific surface area,many surface active sites and high electrocatalytic activity,making them a hot research topic for the construction of sensitive interfaces.Transition metal sulphides（TMS）have received much attention due to their excellent electrochemical properties,abundant reserve resources and environmental friendliness.In this thesis,bimetallic sulphide-based nanomaterials were used to construct a sensitive interface for electrochemical detection applied to the detection of Pb（II）in Chinese herbal medicine samples（1）As Co₉S₈ has excellent catalytic properties,Mo S₂ has good adsorption for Pb（II）.In this experiment,a Co₉S₈@Mo S₂ sensitive interface was synthesized and constructed for the highly sensitive detection of Pb（II）based on the above two materials.Co₉S₈@Mo S₂ not only possesses the advantages of a single component,but also shows excellent detection by improving the electrochemical properties and enhancing the structural stability through the synergistic interaction between components.The electron-feeding ability of Co₉S₈@Mo S₂ was confirmed by XPS and other detection means,which promoted the reduction of Pb（II）by Co₉S₈@Mo S₂.Under the optimal detection conditions,a sensitivity of 103.3±0.5μAμM^-1 and a limit of detection（LOD）of 0.01μM were obtained,and the assay results met the detection requirements set by WHO.In addition,the stability and reproducibility of the assay results were satisfactory.The application of the electrochemical sensing interface constructed in this study to the detection of Pb（II）in Chinese herbal medicine samples provides a new idea for the detection of Pb（II）in Chinese herbal medicine.（2）In this study,a Mo S₂@Co₃S₄ sensitive interface was synthesized and constructed for the detection and analysis of Pb（II）in Chinese herbal medicines.The optimum conditions of the detection process were optimised to achieve a sensitivity of64.64±0.54μAμM^-1 and a detection limit of 0.02μM.The experimental results of the adsorption of heavy metal ions by Mo S₂@Co₃S₄ using XPS revealed that the method has better detection of Pb（II）than other heavy metal ions.The better detection of Pb（II）may be due to the better adsorption performance of Mo S₂@Co₃S₄ on Pb（II）.The results for the herbal samples showed a sensitivity of 64.64±0.54μAμM^-1,which was essentially the same as in the buffer solution,with a linearity of R²=0.994 and a recovery between 90%and 110%,indicating that the electrochemical sensor constructed from this material has great potential for application to the detection of actual herbal samples.