Application Of Sensing Based On Graphene Nanocomposites

Graphene is a new carbon material.It has some unique properties than other nanomaterials,including its larger specific surface area than ordinary materials,excellent electrical conductivity,and good stability.Researchers can use these properties of graphene in various fields,especially in the field of sensing,to build a lot of graphene-based chemical biosensors.Metal nanomaterials also have unique properties that other materials.Combining graphene with metal nanomaterials allows them to have a certain coordination effect,which can more efficiently improve the performance of the sensors prepared.In this paper,three graphene nanocomposites were successfully prepared by combining metal nanoparticles with graphene,and based on this,a sensor platform was established to detect target molecules.The main work includes:?1?The Au-Hg amalgam anchored on the surface of reduced graphene oxide nanosheets?Au-Hg/rGO?have been synthesized successfully and characterized by various techniques like transmission electron microscopy,X-ray diffraction pattern and X-ray photoelectron spectroscopy.The Au-Hg/rGO nanocomposites were found to possess excellent peroxidase-like catalytic activity and can quickly catalyze the oxidization of colorless 3,3',5,5'-tetramethylbenzidine?TMB?into a blue oxTMB in the presence of H₂O₂.The obvious color change offered accurate determination of H₂O₂ concentration by recording the absorbance at 652 nm using a UV-vis spectrophotometer.The linear response range for H₂O₂ was from 5?M to 100?M and the detection limit was 3.25?M?S/N=3?.Furthermore,kinetic study indicated that the catalytic behavior of Au-Hg/rGO nanocomposites followed typical Michaelis-Menten theory and Au-Hg/rGO nanocomposites showed good affinity for H₂O₂.We envision that the simply and sensitively colorimetric detection system holds great promising applications in clinical diagnostics and food environment monitoring.?2?Bimetallic Ag-Pt nanoparticles decorated on the surface of reduced graphene oxide?rGO?were designed and selected as a nanozyme to detect hydrogen peroxide?H₂O₂?.Ag-Pt/rGO nanocomposites were prepared by a simple ultraviolet?UV?irradiation method.The successful formation of Ag-Pt/rGO nanocomposites were confirmed by transmission electron microscopy?TEM?,energy disperse spectroscopy?EDS?mapping,X-ray photoelectron spectroscopy?XPS?and X-ray diffraction?XRD?analysis.Significantly,Ag-Pt/rGO nanocomposites possessed excellent peroxidase-like activity towards the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine?TMB?to form a blue product in the presence of H₂O₂.Moreover,steady-state kinetics studies suggested that Ag-Pt/rGO nanocomposites had high affinity to H₂O₂.Based on these properties,a simple,sensitivity and efficient colorimetric sensor for the detection of H₂O₂ was worked.Under optimal conditions,the constructed H₂O₂ sensor provided the wide linear range?10-100?M,100?M-1mM?and the low detection limit?0.9?M?,as well as high selectivity and stability.Thus,the Ag-Pt/rGO nanocomposites can be used as nanozyme for a wide range of promising applications.?3?Au-Bi nanomaterials were synthesized by a simple method and mixed with GO to obtain Au-Bi/rGO rice composites.Based on this composite material,a new type of electrochemical sensor was constructed to measure Pb²⁺and Cd²⁺.Due to the synergistic effect of Au-Bi NPs and graphene oxide,the modified electrode showed a wide linear range?2-600?M?(Cd²⁺),?0.6-400?M?(Pb²⁺)and a low detection limit?0.79?M?0.08?M?,And successfully applied to the detection of Pb2+ and Cd2+ in actual water samples.