Novel Graphene-Based Composites Application In The Construction Of Electrochemical Sensing Platform

Graphene,as an excellent two-dimensional carbon nanomaterial,has important applications in electrochemical sensors because of its unique structure and excellent electrical properties.Graphene derivatives,such as graphene oxide?GO?,have abundant oxygen functional groups.GO provides many active sites and can make composites with various materials,which not only enhances the function of GO but also develops the advantages of other materials.Graphene-based composites have good catalytic performance and high sensitivity and can adapt to different electrochemical sensing systems.Transition metals and their derivatives possess many merit such as high abundance,low cost,superior electrical properties,and strong electrocatalytic activity.Therefore,the type of composite material consisting of graphene and transition metals or their derivatives has great application prospects in the field of electrochemical sensing.In this paper,several graphene-based composites based on graphene and transition metal derivatives were prepared and applied to the construction of electrochemical sensing platform.The proposed synthesized method of graphene-based composites is very simple.Moreover,when they are used in electrochemical sensors,these prepared composites have many advantages including high catalytic ability,fast response,high sensitivity,good selectivity and can be used for analysis of real samples.The details are as follows:1?Firstly,the electroreduced graphene oxide?ERGO?modified electrode was prepared by green electrochemical reduction method.Then,a metal organic framework?MOF?of the type copper?II?-1,3,5-benzenetricarboxylic acid?Cu-BTC?was electrodeposited onto graphene surface.Thus,an electrochemcial sensing system was constructed for the highly sensitive detection of 2,4,6-trinitrophenol?TNP?and hydrogen peroxide?H₂O₂?.The fabrication process of the modified was characterized by scanning electron microscopy and electrochemical impedance spectroscopy.The monitoring of TNP and H₂O₂ were performed by differential pulse voltammetry and current-time curve,respectively.The results show that the composite has the best catalytic performance based on the synergistic action of Cu-BTC MOF and ERGO,and can be used for the sensitive and selective detection of TNP and H₂O₂ with detection limits of 0.1?M and 1.1?M,respectively.The sensor has also been successfully applied to the quantitative analysis of TNP and H₂O₂ in practical samples.2?A highly efficient non-noble metal electrochemical catalyst,nickel hydroxide/reduced graphene oxide?Ni?OH?₂/sr-GO?nanocomposite,was successfully prepared by a simple one-step solvothermal method without introducing reductant and alkali.The structure and composition of the composite were analyzed by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,X-ray energy spectrum and X-ray photoelectron spectroscopy.Ni?OH?₂/sr-GO was used to construct an enzymatic-free electrochemical sensor by simple dropping method and to determine nitrite with high sensitivity.The result displays that the nanocomposite possesses superior electrocatalytic ability toward nitrite.Under the optimal conditions,the enzymatic-free electrochemical sensor for nitrite detection exhibits a linear range from 0.1 to 663.6?M,with a detection limit of 0.07?M.In addition,the sensor exhibits satisfactory selectivity,reproducibility and stability,and can be used to detect nitrite in water samples.3?Manganese dioxide/electrochemically reduced graphene oxide?MnO₂/ERGO?nanocomposites were prepared by electrochemical method,and then used to construct a novel and facile ratiometric electrochemical sensor for tert-butylhydroquinone?TBHQ?detection.In this work,MnO₂ was used as an internal reference probe for the first time.Firstly,ERGO was prepared by electrochemical reduction of graphene oxide.Then,MnO₂ nanoparticles were deposited on ERGO surface by electrodeposition strategy.The construction process of the modified electrode was characterized by scanning electron microscopy,energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and Raman spectroscopy.Differential pulse voltammetry was used to record electrochemical response signals.The experimental results show that MnO₂ can be used as an internal reference electrochemical probe and ERGO can improve the sensitivity of TBHQ detection.It can be found that with the increasing concentration of TBHQ,the oxidation peak current of TBHQ increases,while the oxidation peak current of MnO₂ remains unchanged.The net peak current ratio between TBHQ and MnO₂ is chosen for quantitative detection of TBHQ.The results show that the linear range is 1.0⁵.0?M,and the detection limit is 0.8?M.In addition,the ratio electrochemical sensor has been successfully applied to the detection of TBHQ in real edible oil samples.