The Electrochemical Properties Study And Application Of Doped Silicon Carbide Nanodiamond

Nanodiamond is widely used in machinery,energy and other fields.In the field of electronics,nanodiamond still has applications.However,and nanodiamond is an insulator with poor electrical conductivity,its application scope is greatly limited.Therefore,in this paper,the conductivity of nanodiamond was enhanced by doping silicon carbide,and its defects were effectively improved,making it an electrode material with wide potential window,low background current and high electrochemical stability.It has a wide application in the electronic field and can be used to detect the concentration of ascorbic acid in organic compounds.In this paper,doped silicon carbide nanodiamond(SiC@NND)was prepared by detonation method,and its electrochemical properties were studied.SiC@ND modified electrode was prepared to detect the concentration of ascorbic acid.The main research content were as follows:(1)This article used the method of perchloric acid to purify doped silicon carbide nanodiamond and nanodiamond(ND),after purification of the SiC@ND and ND respectively,through X-ray diffraction(XRD),infrared spectrum(IR),Raman spectroscopy(Raman),X-ray photoelectron spectroscopy(XPS)characterization,XRD characterization indicated that SiC@ND contained diamond crystal and silicon carbide crystal phase;IR characterization showed that the SiC@ND contained Si-O bonds.Raman characterization showed that after doping with silicon carbide,the content of diamond increased while the content of graphite decreased.XPS characterization showed that silicon carbide was successfully doped into the nanodiamond,resulting in a new C-O-Si structure.Silicon carbide was doped into the nanodiamond in the form of C-O-Si bond,the content of silicon atom was 6.67%,and the silicon element mainly existed in the form of C-O-Si bond and C-Si bond.TEM results showed that nanodiamond is dispersed as a single particle and no agglomeration occurs.(2)To study SiC@ND and ND modified electrode potential window,SiC@ND electrode potential window was 3.6V,and ND modified electrode potential window was 3.1V,compared with a ND modified electrodes,SiC@ND modified electrode potential window increased approximately 20%,which suggested that SiC@ND modified electrodes owned wider potential window,and had more excellent electrochemical performance.In the cyclic volt-ampere curve at different scanning speeds,the ratio between the oxidation peak current density and the reduction peak current density was close to 1,indicating that the reaction of K4[Fe(CN)6]on SiC@ND modified electrode was a quasi-reversibCe reaction.The linear relationship between IP and VU/2 indicated that SiC@ND modified electrode was controlled by diffusion step.The potential window of electrolyte at different pH(2,7,11)was studied.The widest potential window was measured by SiC@ND modified electrode at pH 7.The EIS results showed that the straight line slope of the ND modified electrode was higher than that of the SiC@ND modified electrode,indicating that the diffusion ability of the electrode material decreased after the doping of SiC.High temperature heat treatment SiC@ND under vacuum conditions,XRD and Raman characterization result showed that diamond content reduced,and graphite content increased,SiC@ND electrode potential window with the graphite content increased.(3)In the linear voltammetry curves of SiC@ND and ND modified electrode,the peak current density of SiC@ND modified electrode was the larger,indicating that SiC@ND modified electrode had the higher response to ascorbic acid solution.In the linear voltammetry curve of SiC@ND modified electrode at different ascorbic acid concentrations,the relation between the oxidation peak current and ascorbic acid concentration was:Ip(?A)= 202.38C0(mM)-0.4615,correlation coefficient 0.998,minimum detection limit of 6×10-6 M,so the concentration of ascorbic acid can be detected using SiC@ND modified electrode.PH has a great influence on the potential window,which changes with the change of pH.Under acidic and neutral conditions,the oxidation peak current density and response degree of SiC@ND modified electrode was the highest when pH was 5.SiC@ND modified electrodes under different temperature treatment on the detection of ascorbic acid concentration,the oxidation peak current is strongest at 900 degree and response is the highest.The repeatability test indicated that the SiC@ND modified electrode had a good reproducibility.