Preparation And Application Of Metal Nanomaterials And Its Composite In Electroanalytical Chemistry

The metal nanomaterials is a new kind of multi-functional material which has physical and chemical properties of metal and the basic characteristics of nanomaterials.It has been widely used in many fields since metal nanomaterials birth.Structurally,MWCNTs can be seen as made of multilayer nested SWCNT,it can obtain carbon nanotubes with various functions by modified.In this work,we fabricated different sensors according to remarkable features of above-mentioned materials and researched the detection for nitrite ground on sensors.Through the relevant experiments,in this article,the direct electrochemical behavior of nitrite at a Au nanoparticles(AuNPs)/carbon paper(CP)electrode made using a rapid electrochemical deposition method was investigated.The morphology of the AuNPs on the CP surface was characterized by scanning electron microscopy(SEM).The existence of the Au element was verified by energy dispersive spectroscopy(EDS).The crystal structure of the AuNPs was verified by X-ray diffraction(XRD).Cyclic voltammetry(CV)was applied to evaluate the electrochemical behavior of nitrite oxidation.Under the optimum conditions,the AuNPs/CP electrode exhibited a very strong response to nitrite;the oxidation peak current linearly increased with increasing nitrite in the ranges of 1 mM to 30 mM and 40 mM to 100 mM with correlation coefficients of 0.99883 and 0.99789,and a low detection limit of 0.093 mM.The suggested sensor demonstrated high sensitivity,good reproducibility and good recovery.Ag nanoparticles decorated multi-walled carbon nanotubes(MWCNTs)composite was prepared by a simple electrochemical deposition approach.Transmission electron microscopy(TEM)and Energy dispersive spectroscopy(EDS)were employed to characterize the morphology and composition of the composite.The results showed that Ag nanoparticles with an average size approximately 20 nm were uniformly deposited on the MWCNTs surface.The electrochemical performance of the suggested sensor was investigated via differential pulse voltammetry(DPV)and chronoamperometry.Under optimum conditions,the AgNPs/MWCNTs/GCE displayed a rapid current response to nitrite,with the anodic peak current varying linearly with nitrite concentration in the range of 1 mM～100 mM(R=0.9989)accompanying a low detection limit of 0.095 mM.The long-term stability and good reproducibility were also achieved on the proposed sensor.The determination of nitrite in tap water was studied and showed desirable recovery rate,signifying its possibility for practical application.An electrochemical sensor ground on nickel oxide(NiO)nanoparticles and multi-walled carbon nanotubes(MWCNTs)was exploited for the detection of nitrite.Scanning electron microscopy(SEM)ensure the morphology of the nanocomposite consisted of NiO nanoparticle and MWCNTs.High Resolution Transmission electron microscopy(HR-TEM)reveals that the structure of NiO nanoparticles and MWCNTs.Scanning transmission electron microscopy(STEM)persuasively verified presence of the C,Ni and O element.The electrochemical character of the nanocomposite was researched by cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS),and the behavior of electrochemical oxidation to nitrite on NiO/MWCNTs/CP was explored by chronoamperometry.In tests,the NiO/MWCNTs/CP shown a sensitive current response toward nitrite,the oxidation peak current are linearly related to nitrite concentration in the range from 10-6 M to 10-4 M(R=0.997)with a sensitivity of 3.53 μA μM-1 and a detection limit of 0.25μM(S/N=3).The validity of utilizing the proposed electrode to determine nitrite in tap water was also demonstrated.Nano-composite of gold(Au)/nickel oxide(NiO)were loaded on multi-walled carbon nanotubes(MWCNTs)to modified carbon paper(CP)are constructed by utilizing a relatively facile and straightforward electrochemical deposition method.Transmission electron microscopy(TEM)reveals that the nanocomposites of Au/NiO with an average size around 58 nm are covered on the MWCNTs surface.Scanning transmission electron microscopy(STEM)convincingly demonstrated presence of the C,Au,Ni and O element.The electrochemical performance of the proposed electrode is investigated via cyclic voltammetry(CV)and chronoamperometry.In tests,the Au/NiO/MWCNTs/CP exposed an obvious current response toward nitrite,the anodic peak current in proportion with nitrite concentration ranging from 0.1 μM to 1 μM(R=0.99865)with a low detection limit of 0.02 μM(S/N=3).The prepared electrode possessed great stability and reproducibility.It was triumphantly applied to the detection of nitrite in tap water represent its feasibility on specific application.