Preparation Of Vanadium Sulfide Nanosheet Spheres/graphene Composite And Electrochemical Detection Of Epinephrine

Vanadium sulfide（VS₂）is a layered two-dimensional transition metal compound material that exhibits certain metallic properties with multiple valence states and high catalytic activity.It has a wide range of applications in electrochemical energy storage,biosensors,and electrochemical water splitting for hydrogen desorption.However,transition metal compounds generally have a serious problem of poor electrical conductivity.By compounding a material with high electrical conductivity,this key problem can be effectively improved and solved by using its synergistic effect.In this article,we first prepared graphene oxide（GO）by a modified Hummer’s method,and then anchored three-dimensional rosette-like vanadium sulfide nanosheet spheres on reduced graphene oxide（RGO）by a one-step hydrothermal method.The vanadium sulfide nanosheet spheres（VS₂ NSSs）can provide a large specific surface area,abundant active sites and excellent catalytic activity,the reduced graphene oxide can improve the electrical conductivity of the composite,thereby improving the electrochemical performance of the composite.The morphology of the composite structure was characterized by scanning and transmission electron microscopy.It can be observed that the diameter of the VS₂ NSSs is 5μm,and the thickness of the nanosheets is 200 nm.The VS₂ NSSs was uniformly anchored on the RGO,and the RGO are all lamellar structures.In addition,Raman spectroscopy and X-ray diffraction were used to analyze the structure of VS₂NSSs/RGO.The results verified the successful preparation of the composite.The VS₂ NSSs/RGO/ITO electrode was prepared by spraying on indium oxide glass（ITO）,and followed by heat treatment.Further,the composites electrode is used to detect the active biomolecule epinephrine（EP）.The electrochemical methods mainly include cyclic voltammetry（CV）,differential pulse voltammetry（DPV）and electrochemical impedance spectroscopy（EIS）.Finally,the electrode showed a sensitive electrochemical response to EP analytes.In the range of EP（0-60μM）,it showed a high sensitivity of 1.385μA·μM^-1 and a detection limit as low as 0.017μM.At the same time,the electrode also shows excellent selectivity,repeatability and stability.In addition,the VS₂ NSSs/RGO/ITO electrode has successfully detected EP in human blood.The results show that the composites have a great potential for clinical testing.