Preparation,Characterization And Performance Of Surface Renewable And Reusable Electrochemical Sensors Based On PW₁₁Fe

In the field of electrochemical sensor,it is a difficult problem and challenge to prepare a new kind of high sensitivity electrode which can be updated and reused.In order to solve this problem,this paper is divided into two steps.Firstly,by sol-gel method with Keggin type Fe?III?-substituted heteropoly anion PW₁₁O₃₉Fe?III??H₂O?^4-(PW₁₁Fe)as the active component,chitosan?CS?as adsorbent and binder,and carbon nano tubes?CNTs?as conductive additive,the PW₁₁Fe/CS/CNTs/C composite electrode?CE?was prepared.The electrochemical behavior of the electrode was investigated by cyclic voltammetry,electrochemical impedance spectroscopy and chronoamperometry.The electrocatalytic activity of H₂O₂ and the sensing properties of H₂O₂ were studied.The experimental results show that the electrochemical behavior of PW₁₁Fe in homogeneous aqueous solution and the electrocatalytic activity for H₂O₂ reduction are retained.For the detection of H₂O₂,the response current of PW₁₁Fe/CS/CNTs/C CE was in the range of5³5?M,and the concentration of H₂O₂ was linear.The sensitivity and detection limits were 0.30 m A/cm².?M and 7.3?M?S/N=3?respectively.Because of the electrocatalytic activity of the electrode,the adhesive is attached to the surface of the graphite electrode,and can not be subjected to surface polishing and ultrasonic cleaning.Therefore,the surface can not be updated and reused when the electrode surface is contaminated.In order to solve the above problems,the improvement was carried out on the basis of PW₁₁Fe/CS/CNTs/C CE.reduction of graphene oxide?RGO?was dispersed into PW₁₁Fe solution to prepare PW₁₁Fe/RGO composite,by using methyltrimethoxysilane?MTM?as crosslinking agent,the PW₁₁Fe/RGO/MTM CE was prepared by sol-gel method.The electrochemical behavior of PW₁₁Fe/RGO/MTM CE was investigated by cyclic voltammetry,electrochemical impedance spectroscopy and chronoamperometry.The electrocatalytic activity of H₂O₂ and the sensing properties of H₂O₂ and glucose were studied.The experimental results show that PW₁₁Fe/RGO/MTM CE can maintain the electrochemical behavior of PW₁₁Fe in homogeneous aqueous solution and the electrocatalytic activity for the reduction of H₂O₂,at the same time,can also be through simple surface polishing on the surface of electrode update.For the detection of H₂O₂,the response current of PW₁₁Fe/RGO/MTM CE was in the range of 0.6⁵.0 m M,and the concentration of H₂O₂ was linear.The sensitivity and detection limits were 1.338?A/m M and 0.52 m M?S/N=3?respectively.For the detection of glucose,the response current of PW₁₁Fe/RGO/MTM CE was in the range of 4.5³0?M,and the concentration of hydrogen peroxide was linear.The sensitivity and detection limits were 0.034?A/?M and2.206?M?S/N=3?respectively.However,in the course of the experiment,it is found that PW₁₁Fe/RGO/MTM CE has a certain degree of reuse,but there is still the problem of electrode surface PW₁₁Fe leakage in the experiment.Therefore,the PW₁₁Fe insoluble cesium salt instead of PW₁₁Fe as active components in electrocatalysis,MTM as crosslinking agent,RGO as conductive additives,the Cs PW₁₁Fe/RGO/MTM CE was synthesized by sol-gel method and ball milling method.The electrochemical behavior of the electrode was investigated by cyclic voltammetry,electrochemical impedance spectroscopy and chronoamperometry.The electrocatalytic activity of H₂O₂ and the sensing properties of H₂O₂ and glucose were studied.The experimental results show that the electrode can not only be subjected to surface polishing and ultrasonic cleaning,but also maintain the electrochemical behavior of PW₁₁Fe in homogeneous aqueous solution and the electrocatalytic activity for H₂O₂ reduction.For the detection of H₂O₂,the response current of PW₁₁Fe/RGO/MTM CE was in the range of 0.6⁵.0 m M,and the concentration of H₂O₂ was linear.The sensitivity and detection limits were 1.89?A/m M and 0.49 m M?S/N=3?respectively.For the detection of glucose,the response current of PW₁₁Fe/RGO/MTM CE was in the range of 4.5³0?M,and the concentration of hydrogen peroxide was linear.The sensitivity and detection limits were 0.26?A/?M and0.34?M?S/N=3?respectively.