Self-assembled Technology And Its Application For The Determination Of Small Biomolecules And The Corrosion Inhibition Of Copper

Self-assembled monolayer (SAM) films are molecular aggregates that are spontaneously formed by the adsorption of amphifunctional molecules on a solid surface. Fabrication and characterization of SAM have made great progress in the past 20 years. In this article, one principal research is about the gold electrode modified with L-cysteine and its application, and the other is about the application of self-assembly in the corrosion inhibition of copper. The main research work is as follows:1. Electrocatalytic oxidation and determination of uric acid on the L-cysteine self-assembled monolayer modified gold electrodeThe fabrication and electrochemical characteristics of L-cysteine self-assembled monolayer modified gold electrode were investigated. The self-assembled electrode showed an obvious electrocatalytic activity for the oxidation of uric acid. Under the optimum conditions, the peak current was linear to the concentration of uric acid in a certain range. The L-cysteine self-assembled monolayer modified gold electrode had a high stability and can be applied to the determination of uric acid in practical samples with simplicity, rapidness and accuracy.2. Simultaneous determination of uric acid and epinephrine on L-cysteine self-assembled monolayer gold electrodeThe electrochemical behaviors of epinephrine (EP) and uric acid (UA) at the L-cysteine self-assembled monolayer modified gold electrode have been studied by the differential pulse voltammetry method. The modified electrode showed an excellent electrocatalytic activity for the simultaneous oxidation of EP and UA in phosphate buffer of pH 7.7. It could accelerate electron transfer rate. This electrode exhibits a potent and persistent electronmediating behavior followed by well-separated oxidation peaks towards UA and EP with a potential difference of 316 mV, which is large enough to determine UA and EP individually and simultaneously. Under the optimum conditions, the detection limit of epinephrine is EP was 2.4×10^-7 mol l^-1 and that of uric acid is UA was 6.5×10^-7 mol l^-1. The L-cysteine self-assembled monolayer modified gold electrode has a high stability and can be applied to the determination in practical samples with simplicity, rapidness and accurate results.4. Study on the corrosion inhibition behavior of 1,3-benzenedithiol on copperThe corrosion inhibition efficiency of 1,3-benzenedithiol (BDT) on copper in 3%NaCl solution was studied by electrochemical measurement. The experimental results indicated that BDT had good corrosion inhibition on copper. Inhibition efficiency was different with the change in the pH of 3%NaCl solution and the self-assembled time. It was the best when copper was modified with 2.0×10^-3 mol l^-1 1,3-benzenedithiol for 40 h.5. Electrochemical studies for the self-assembled film of 2,5-dimercapto-l, 3, 4-thiadiazole on copperThe self-assembled film of 2,5-dimercapto-1,3,4-thiadiazol (DMTD) was prepared on copper surface. Electrochemical methods were performed to characterize the inhibition efficiency. It was the greatest when the copper electrode was modified with 2.0×10^-3 mol l^-1 DMTD for 24 h. The experimental results showed that its inhibition efficiency was different with the variation of self-assembled time and the pH of NaCl solution.6. Corrosion inhibition of the 1,6-hexanedithiol self-assembled film on copperThe corrosion inhibition effect of 1,6-hexanedithiol (HDT) self-assembled film on copper in 3 % NaCl solution was studied by electrochemical method. The experimental results showed that inhibition efficiency was different with the variation of self-assembled time and the pH of 3 % NaCl solution. When the copper electrode was modified with 2.0×10^-3 mol l^-1 HDT for 50 h, the corrosion current density of the electrode was the lowest and the inhibition efficiency reached the highest.