Electrochemical Preparation Of The Modified Electrode Coated With Nitrogen-containing Organic Polymers/3d-4f Cyanide-bridged Heterometal Coordination Polymers And Its Electroanalytical Application For Some Metalloid Element Ions

As a novel electrode modification materals,the 3d-4f cyanide-bridged heterometal coordination polymers（3d-4f CyHMCPs）,in which the lanthanide rare earth ions usually exist,have been partially applied in the field of electroanalysis and electrocatalysis.In this dissertation,the Nitrogen-containing organic polymers and 3d-4f cyanide-bridged heterometal coordination polymers have been simultaneously modified on a glassy carbon electrode by the multi-step electrosynthesis method,a novel composite modified electrode,Nitrogen-containing organic polymers/Nd（Ⅲ）-Fe（Ⅲ）-Pb（Ⅱ）-CrO₄^2-CyHMCPs/GCE,is successfully prepared.Furthermore,a profound study can be made on the voltammetric characteristics of several metalloid element ions at this modified electrode,and some electroanalysis methods for selenium,tellurium,and indium ions are preliminarily established.When modifing both Nitrogen-containing organic polymers and 3d-4f cyanide-bridged heterometal coordination polymers onto the electrode substrate.On the one hand,the synergetic action existed in the various modified materials can greatly enhance the electrocatalytic activity and stability of the working electrode;On the other hand,the durability and service life of the working electrode can also be improved by enhancing the adhesion strength between the electrocatalyst materials layers and the electrode substrate.Due to the unique electrocatalytic activity,more wider potential window and large overpotential for hydrogen ions reduction about the of 3d-4f cyanide-bridged heterometal coordination polymers materals,in this experiments,we have found that Se（Ⅵ）and Te（Ⅵ）ions can make the underpotential deposition on this modified electrode,and produce the well-defined cathodic catalytic waves through the intermediates of the hydrogen selenide or hydrogen telluride from the electroreduction reaction.Based on this conclusions,we have established new quantitative methods for Se（Ⅵ）and Te（Ⅵ）ions,and also develope a anodic stripping analysis method for indium ions using the in-situ plating bismuth-film technique.Firstly,the new composite modified electrode,poly（Ninhydrin-γ-aminobutyric acid）/Nd（Ⅲ）-Fe（Ⅲ）-Pb（Ⅱ）-CrO₄^2-CyHMCPs/GCE,is prepared by using a multi-step electrosynthesis method,and its apparent morphology has been characterized by scanning electron microscopy（SEM）.All of experimental conditions for preparing the composite modified electrode can be carefully optimized using the peak current value of the cathode catalytic wave of Se（Ⅵ）as the optimization parameter.Moreover,with the composite modified electrode as the working electrode,the composition and concentration about the supporting electrolyte solution have optimized by differential pulse voltammetry（DPV）.The effects of deposition potential and deposition time on the response peak current of Se（Ⅵ）were investigated.Under the optimal experimental conditions,the electrocatalytic reduction peak current of Se（Ⅵ）has direct proportion with their concentration ranging from 5.00～70.0μmo L/L,and the linear regression equation is Ip（μA）=-0.814+0.206C_Se（Ⅵ）（μmo L/L）,R²=0.9993.The lowest detect limit（LOD）is 0.43μmo L/L（S/N=3）.Based on the results,a new quantitative method for the trace Se（Ⅵ）was established.When a national standard sample is used for the validity of this method,the obtained recovery is of 97.7%～102%,and the results are satisfactory.Next,using the mixed solution containg both ninhydrin and homocystine acid with their moler ratio of 1:2 as the electroplating solution,we can form a poly（Ninhydrin-homocystine acid）basic layer on a glassy carbon substrate,then material layer of neodymium-containing cyanide-bridged heterometal coordination polymers is prepared again by cyclic voltammetry,a new modified electrode,poly（Ninhydrin-homocystine acid）/Nd（Ⅲ）-Fe（Ⅲ）-Pb（Ⅱ）-CrO₄^2-CyHMCPs/GCE,will be successfully obtained.With this modified electrode as a working electrode,an analytic method for Te（Ⅵ）has established by differential pulse voltammetry（DPV）.Under optimized testing conditions,the electrocatalytic reduction peak current of Te（Ⅵ）has direct proportion with their concentration ranging from 10.0～180μmo L/L,and the linear regression equation is Ip（μA）=-1.957+0.182 C_Te（Ⅵ）（μmo L/L）,R²=0.9931.The lowest detect limit（LOD）is 0.32μmo L/L（S/N=3）.Based on the results,a quantitative method for the trace Te（Ⅵ）has also established.When a national standard sample is used for the validity of this method,the obtained recovery is of 96.2%～102.6%,and the results are satisfactory.Lastly,the poly（Glutamine-glycine）/neodymium-containing cyanide-bridged heterometal coordination polymers composite modified glassy carbon electrode,poly（Glutamine-glycine）/Nd（Ⅲ）-Fe（Ⅲ）-Pb（Ⅱ）-CrO₄^2-CyHMCPs/GCE,was prepared by a multi-step electrosynthesis method.At this modified electrode,the stripping voltammetric characteristics of In（Ⅲ）were studied in-deeply by using in-situ plating bismuth-film differential pulse anodic stripping voltammetry（DPASV）.In addtion,it is found that when adding an appropriate amount of 5-sulfosalicylic acid and potassium bromide to the supporting electrolyte,the interference of co-existing Cd²⁺can be effectively eliminated for the determination of In³⁺.Under the optimal testing conditions,the stripping peak current of In（Ⅲ）has direct proportion with their concentration ranging from 0.01 to 30.0μmo L/L,and the linear regression equation is Ip（μA）=1.135+1.162C_In（Ⅲ）（μmo L/L）,R²=0.9986.The lowest detect limit（LOD）is 0.008μmo L/L（S/N=3）.When validation experiments were conducted on this method,the recovery of national standard samples has a range of100.4%to 101.4%,and the results were satisfactory.