Study On The Electrochemical Behavior Of Small Biomolecules And Corrosion Inhibition Of Nickel

Chemically modified electrodes (CMEs) have had a dominant position in many electrochemical studies since 1970's. This article includes the study on the preparation of the activated glassy carbon electrode and its electrochemical response to small biomolecule, the application of self-assembled films technology in the corrosion inhibition of nickel as well as the test of corrosion inhibition of the self-assembled films to nickel with electrochemical methods. The possible reaction mechanism has also been discussed.The research work is as follows:1. Study on the activated glassy carbon electrode and its applicationAfter the glassy carbon electrode is electrochemically pretreated, there are some oxygen groups, such as carbonyl, carboxyl group, and phenol hydroxyl on the surface of the activated glassy carbon electrode. The existence of these groups will improve the performance of the activated electrode. Compared with the bare glassy carbon electrode, the response of pretreated glassy carbon electrode to dopamine is enhanced. Moreover, this activated electrode can simultaneously determine the epinephrine and the uric acid by differential pulse voltammetry. This electrode exhibits a potent and persistent electronmediating behavior followed by well-separated oxidation peaks towards epinephrine and uric acid with a potential difference of 161 mV, which is large enough to determine epinephrine and uric acid individually and simultaneously. Under the optimum conditions, the detection limit of epinephrine is 8.9×10^-8mol L^-1 and that of uric acid is 1.6×10^-7mol L^-1. The proposed method was successfully used for the determination of epinephrine and uric acid in real samples with satisfactory results. 2. Corrosion inhibition effect of the uric acid self-assembled film to nickelThe corrosion inhibition effect of the uric acid self-assembled film to nickel in 3% NaCl solution was studied by electrochemical methods. The experimental results showed that uric acid mainly suppressed the anodic reaction and its inhibition efficiency was different with the variation of uric acid concentration, self-assembled time as well as the pH of uric acid solution. When the nickel electrode was modified with 0.80 mmol L^-1 uric acid for 12 h at pH 9.00, the corrosion current density of the electrode was the lowest and the inhibition efficiency reached the highest value, 95.7%.3. Study on the corrosion inhibition effect of the melamine self-assembled film to nickelMelamine is one kind of important industrial chemicals and there are many amido groups in the melamine molecules. The experimental results show that nickel can be attached by these amido groups to form compact film in the nickel surface; therefore, the surface impedance of nickel increases, the corrosion current decreases, the corrosion potential moves to positive direction, and the inhibition efficiency reaches the highest value, 98.61%. The inhibition efficiency is different with the variation of melamine concentration, self-assembled time as well as the pH of melamine solution. When the nickel electrode was modified with 3.0 mmol L^-1 melamine for 72 h at pH 6.50, the corrosion current density of the electrode was the lowest.