Study On The Surface Treatment Of Nichrome Substrate And Application

Recently, electrochemical analysis methods were applied more and more widely in differentresearch fields, actual production and life. All these methods use electrode to convert quantity data toelectro-signals which could be measured. Thus, the work electrode as the focus become a hot research area.When traditional bare electrodes exposed various defects, they were already far from satisfying the actualneed. The surface treatment of electrode, as the improvement and optimization way for traditional electrode,are attractting more attention from research workers.In this paper, three surface treatment methods based on the nichrome electrode and theapplications of the modifed electrode were reported.Part1: In this paper, nichrome was adopted as a substrate to fabricate the bismuth film/nichromeelectrodes （BNCE） by electrochemical technique. The scanning electron microscope （SEM） was employedto characterize the electrode configuration. BNCE was used for the determination of Pb（II） and Cd（II） withanodic stripping voltammetry. the reaction on the counter electrode in the preconcentration process, and itseffect on the anodic stripping peak current of Pb and Cd at the bismuth film nichrome electrode （BNCE）have also been carefully investigated for the first time. The results revealed that, during thepreconcentration process, the driving force for Pb（II） and Cd（II） transport towards cathode not only relatedto the concentration diffusion but also depended on the concentration of H⁺in the feed phase. Since H⁺isthe resultant of the anode reaction, the anode reaction rate speeds up as the pH of the electrolyte increases,accordingly, the cathode reaction rate is enhanced leads to the increase of the prconcentrated metal, thus itsstripping peak current becomes large.Part2: A new kind of electrode for sensing hydrogen peroxide （H₂O₂） was reported. Silvermicrocrystals were initially deposited on a nichrome substrate by cyclic voltammetry and controlledpotential electrolysis, respectively. Scanning electron microscopy was applied to characterize themorphology of the silver microparticles on the nichrme surface. The micron-silver nichrome electrodeexhibits sensitive electrochemical response to H₂O₂in pH4.5HAc-NaAc buffer solution, and its catalyticactivity is much higher than that of a pure silver electrode. Under the optimum conditions, the well-defined reduction peak current increases linearly with H₂O₂concentration in the range of9.80×10^-5～5.88×10^-3mol/L, and the detection limit is5.8×10^-7mol/L. The electrode can be applied to the voltammetricdetermination of H₂O₂, and recoveries of artificial samples are between99.7%-105.1%.Part3: Nichrome was adopted as a substrate, to fabricate an inlaying ultra-thin carbon pasteelectrode （IUTCPE）. Cyclic voltammetry （CV） and linear scan voltammetry （LSV） were used to investigatethe electrochemical responses of metronidazole （MTZ）. The results revealed that, in0.1mol/L B.R. buffer（pH1.95）, the IUTCPE showed a good electrocatalytic reduction towards MTZ. Under optimized conditions,the well-defined reduction peak currents increased linearly with increasing the contents in the range of7.01×10^-7～1.17×10^-3mol/L. The detection limit （S/N=3） was2.87×10^-7mol/L. IUTCPE has theadvantages of simple procedure, good stability and greatly low cost. The proposed method was successfullyapplied to MTZ determination in tablets, and the recovery was from100.0%to102.2%.Part4: Nichrome was adopted as a substrate to fabricate an inlaying ultra-thin carbon pasteelectrode （IUTCPE）. Electrochemical reduction response of p-nitrophenol（p-NP） at this electrode wasstudied by cyclic voltammetry （CV） and linear scan voltammetry （LSV）. In HCl-KCl buffer solution（pH1.8）, the IUTCPE showed a good electrocatalytic response towards p-NP. The reduction peak currentswere linearly related to the concentration of p-NP over the range of2.0×10^-7～1.0×10-4mol/L, with thedetection limit of2.3×10^-8mol/L. Consequently, a simple and sensitive electrochemical method wasproposed for the determination of p-NP in artificial sample, which was used to determine p-NP in artificialwater sample, and the recovery was from96.1%to106.8%.