Study On Hydrogen Peroxide Electrochemical Sensor Based On MIL-53 Precursor

Hydrogen peroxide（H₂O₂）is an important commercial product,which is widely used in industrial,clinical and other fields.In addition,it is also a human reactive oxygen species and participates in a variety of biochemical reactions in the human body.However,the commercial value of H₂O₂ leads to its massive abuse,which seriously pollutes the environment and human health.Therefore,the country has clear regulations and requirements for the content of H₂O₂ residues,which also makes the real-time,in-situ and continuous detection of H₂O₂ has important practical significance.Traditional detection methods have some shortcomings such as expensive and time-consuming,so it is difficult to meet the above requirements,and the emergence and development of electrochemical sensors provide a favorable way for the detection of H₂O₂.As the performance of the electrochemical sensor mainly depends on the electrode material,it requires that the electrode material for constructing the electrochemical sensor must have some specific properties（such as low detection limit,high stability,low price,etc.）.Metal-organic frame material（MOFs）has unique physical and chemical properties such as high catalytic activity,structural diversity and large specific surface area,which has been successfully applied to the sensor and effectively improved the sensitivity and stability of the sensor.However,the electrical conductivity of pure MOFs material is poor,so it is difficult to be widely used in electrochemical sensors.In order to obtain electrode materials with higher conductivity and stability,three new MOFs composites were prepared by combining carbon with good conductivity,lanthanide metals and transition metals with electrocatalytic properties,and used as electrode materials for electrochemical sensors to carry out a series of studies on the electrocatalytic oxidation of H₂O₂.The main contents of this thesis are as follows:First、Preparation of Fe₂O₃/Ce O₂@CN composite and study on its electrocatalysis of hydrogen peroxideBimetallic MOFs with the same crystal structure as MIL-53 were synthesized by solvothermal synthesis using terephthalic acid（1,4-H₂BDC）as the organic ligand.Using ferric chloride and cerium nitrate as mixed metal sources,by adjusting the reaction time and the reaction amount of cerium nitrate,Fe/Ce-MIL-53 with uniform morphology and containing 1.68 wt%Ce content was prepared,and XRD characterization proof the MOFs is indeed bimetallic MOFs.Fe₂O₃/Ce O₂@CN,was prepared by pyrolysis of dimelamine and Fe/Ce-MIL-53 under the optimum synthesis conditions,and used as the electrode material of modified glassy carbon（GCE）for the first time in electrochemical sensing H₂O₂.The experimental results show that the modified electrode has the advantages of rapid response to H₂O₂ detection,wide detection range（10-190μM）,low detection limit（0.1829μM）,good repeatability and stability.Therefore,this study provides a new idea for the design and development of new electrochemical sensors.Second、Preparation of Fe/Ce/Mn-MIL-53 composite and study on its electrocatalysis of hydrogen peroxideIn order to avoid the loss of active sites caused by pyrolysis,Mn²⁺with the same coordination number as Fe³⁺was selected as the third metal ion source,Mn-doped Fe/Ce-MIL-53 composites were synthesized,and the reaction time and manganese nitrate reaction amount were optimized and related characterization.The Fe/Ce/Mn-MIL-53 synthesized under the optimum conditions was directly modified with GCE for the detection of H₂O₂.The experimental results show that the sensitivity(179.01μA·m M^-1·cm^-2)of the electrode material to H₂O₂ and the detection limit（0.074μM）are better than prepared by pyrolysis Fe₂O₃/Ce O₂@CN,and the detection range（5-175um）and sensitivity are better than other Fe-based MIL series MOFs materials.Third、Preparation of Fe/Ce/Co@CN composite and study on its electrocatalysis of hydrogen peroxideUsing Co²⁺with the same coordination number as Fe³⁺as the third metal source,Fe/Ce/Co-MIL-53 was synthesized by solvothermal method and the reaction amount of cobalt nitrate was optimized.The Fe/Ce/Co@CN material was prepared by pyrolysis of dimelamine and Fe/Ce/Co-MIL-53 synthesized under the optimum conditions,and a new electrochemical sensor for the detection of H₂O₂ was constructed by modifying GCE with Fe/Ce/Co@CN material.The experimental results show that the the electrochemical sensor has a wide linear range（300-1100μM）and low detection limit（0.4144μM）,and the modified electrode has good repeatability and stability.Therefore,Fe/Ce/Co@CN composites have certain application value in the field of H₂O₂ detection.