Synthesis Of Cobalt Based Electrode Modified Materials Using ZIFs As Precursors And Electrochemical Sense Property

Chemically modified electrode?CME?is a conductor or a semiconductor.By coating the electrodes surface with a layer of functional substance,they can obtain certain chemical or electrochemical property to complete the target reaction selectively,which result in their broad applications in the field of life,environment,energy,catalysis,analysis and materials.Among them,CME appeals much attention as electrochemical sensors to detect trace amount of certain ions or molecules by electrochemical analysis method.Therefore,it is extremely critical to obtain CME with high sensitivity and selectivity.Recently,most research focused on the synthesis of modifiers on the substrate electrode surface,and it becomes much important to find a simple and reliable synthetic route to produce the electrodes modified materials with excellent electrocatalytic properties.As a novel class of porous materials,zeolitic imidazolate frameworks?ZIFs?have attracted great concern of researchers due to its large surface area,high stability,adjustable pore size and diverse pore structure.However,previous studies have focused on the synthesis and application of novel ZIFs crystals,and there were less reports about using ZIFs as precursor to obtain other functional materials.Thus,in this paper,nano-porous materials were prepared using ZIF-67 as self-sacrificing template.Then,the obtained nano-materials were modified on glassy carbon electrode?GCE?surface for electrochemical detection of H₂O₂,dopamine?DA?and uric acid?UA?.Uniform ZIF-67 nano-crystals were prepared using coordination modulation method.Then,nano-scaled Co₃O₄ hollow spheres were synthesized by directly calcining ZIF-67precursor under air atmosphere,and the effect of precursor's size on the physical and chemical properties of Co₃O₄ has also been explored.It is found that the Co₃O₄ nanoparticles prepared from ZIF-67 without TEA possess unique hollow spherical structure.The resulting Co₃O₄ hollow sphere was exploited as electrocatalysts for sensitive H₂O₂ detection in an alkaline medium.The Co₃O₄ hollow sphere modified glassy carbon electrode exhibited a fast response time?within 3s?,a high sensitivity of 120.55?A·mM^-1(959.79?A·mM^-1·cm^-1),a broad linear range from 0.4?M to 2.2 mM,a detection limit of 0.105 mM?S/N=3?,and good stability and selectivity,which make great significance on the development of H₂O₂electrochemical sensors.Then,ZIF-67 crystals were carbonized at 600,700,800 and 900?respectively under nitrogen atmosphere to prepare N and Co-doped carbon nanoparticles?NCCNPs?,and the as-obtained NCCNPs were modified on GCE surface to detect DA and UA.It was found that the NCCNPs synthesized at 800?performed best electrocatalytic properties.Firstly,Co counted for a high proportion in NCCNPs₈₀₀ and showed high degree of crystallinity,which provided abundant active sites for electrochemical reaction.Secondly,there existed many pyridinic N with strong electron accepting ability that was beneficial for the electrocatalytic process.Finally,the presence of graphitic N can promote the two-electron process,which will be in favor of electrochemical detection of DA and UA.The results showed that the detection limits and sensitivity for DA and UA of NCCNPs₈₀₀/GCE were 0.34?M and1130.3?A·mM^-1,0.98?M and 610.7?A·m M^-1,respectively.