Preparation Of Porous Graphene And Construction Of Its Electrochemical Sensor

Porous graphene（PG）is one of graphene（G）derivatives.Its pore structure can be divided into two-dimensional（2D）in-plane nanopores and three-dimensional（3D）network micropores.Owing to these pore structures,PG not only possess the good properties of G itself,but also have many unique physical,chemical,electrochemical and other characteristics.In this thesis,three kinds of PG materials were successfully prepared and their electrochemical properties were also systematically studied.Then,PG materials were used to construct NaNO₂ and L-ascorbic acid（LAA）electrochemical sensors.The main research contents and main conclusions are as follows:（1）Constraction of nitrite electrochemical sensor based three dimensional graphene（3D-G）.3D-G was prepared by chemical reduction method.The structure and composition of 3D-G were characterized by UV spectrophotometer（UV-vis）,X-ray photoelectron spectroscopy（XPS）and Raman spectroscopy（Raman）.The results showed that the graphitized sp² domain in 3D-G was significantly increased,and the reduced 3D-G was successfully prepared.The morphology of 3D-G was characterized by scanning electron microscope（SEM）and specific surface area analyzer（Brunner-Emmet-Teller,BET）.The results showed that the 3D-G has abundant of 3D network micropores and a large number of exposed edges,which can effectively avoid G re-agglomeration and increase the specific surface area.The electrochemical properties of 3D-G modified glassy carbon electrode（GCE）were studied by cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）.The results showed that 3D-G with unique 3D network microporous structure effectively improves the electronic transfer（ET）capability and mass transfer capability.3D-G was used to detect NaNO₂ by differential pulse voltammetry（DPV）.The results showed that the electrochemical sensor based on 3D-G has excellent electrocatalytic activity for NaNO₂,high sensitivity,low detection limit and wide linear range.（2）Preparation of electrochemical reduced holey graphene（ERHG）and construction of its electrochemical sensor.ERHG was prepared by photo-Fenton method and electrochemical reduction method.The structure and morphology of ERHG were characterized by transmission electron microscopy（TEM）,Raman and XPS.The results showed that a large number of 2D nanopores were distributed on the basal plane of ERHG,and number of exposed edges and the defect density increased.The electrochemical properties of ERHG modified GCE（ERHG/GCE）were studied by CV and EIS methods.The results showed that ERHG with abundant nanopores can effectively improve the ET capacity and mass transfer capacity.The NaNO₂ electrochemical sensor based on ERHG has excellent electrocatalytic activity for NaNO₂.The linear range of NaNO₂ concentration is 0.2μM-10 m M,and the detection limit is 0.054μM.Moreover,the sensor has excellent anti-interference ability,good repeatability,reproducibility and long-term stability.（3）Preparation of three dimensional holey graphene（3D-HG）and construction of its electrochemical sensors.3D-HG was prepared by hydrothermal method using hydrogen peroxide（H₂O₂）as an etchant.The 3D-HG was characterized by UV-vis,SEM,TEM and BET.The results showed that 3D-HG has abundant of 3D network micropores and a large number of 2D basal nanopores,which increase the number of exposed edges,effectively avoid G re-agglomeration and increase the specific surface area.The electrochemical properties of 3D-HG modified GCE（3D-HG/GCE）were studied by CV and EIS.The results showed that the abundant of 3D network micropores and a large number of 2D basal nanopores of 3D-HG significantly improve the electrode ET capacity and mass transfer capacity.Based on the excellent electrochemical performance of 3D-HG,LAA electrochemical sensor and NaNO₂ electrochemical sensor were constructed,which showed good electrocatalytic performance for both LAA and NaNO₂.The 3D-HG-based electrochemical sensors has excellent sensitivity,wide linear range,strong anti-interference ability and good reproducibility.