SERS Studies On The Adsorption And Film Formation Of NMIM And BIMH In Non-aqueous System

Surface-enhanced Raman Spectroscopy (SERS) is one of the most sensitive techniques for probing the structure of electrochemical interfaces. Especially, in situ SERS can provide detailed information about the adsorption mechanism on metal surfaces at molecular level. Due to the important role of inhibitors in the fundamental studies and application in non-aqueous solution, the adsorption behavior and surface coordination of inhibitors on Cu and Ni electrode surfaces are investigated by electrochemistry and SERS. The main results and conclusions of the dissertation are listed as follow:1. The adsorption behavior and coadsorption of N-methylimidazole (NMIM) and 2,2'-bipyridine (2,2'-bipy) at Cu electrode were investigated by in situ electrochemical SERS in the acetonitrile solution. It revealed that NMIM adsorbed onto Cu electrode in the wide potential range: (a) negative than -0.6 V, NMIM molecule absorption with a tilted orientation, (b) positive than 0.1 V, film formation of NMIM and attached on Cu surface, (c) between -0.6 V and 0.1V, NMIM molecule adsorption transformed into film formation. With the introduction of 2,2'-bipy, the interfacial structure could be divided into three parts: (a) under -0.8V, NMIM adsorbed with neutral molecule, (b) near the open potential, 2,2'-bipy adsorbed with cis-conformation (c) at positive potential region, both NMIM and 2,2'-bipy were coadsorbed at Cu surface, the NMIM bound to Cu surface with a tilted orientation, while the 2,2'-bipy was absorbed through cis-conformation. The surface complex was synthesized in the similar condition with the structure of [(2,2'-bipy)Cu(NMIM)2](NO3)2. Two N atoms from each dentate ligand 2,2'-bipy bridges the central Cu(II) ion with cis- conformation and two N atoms from two NMIM molecules were coordinated to the same Cu(II) ion, which was well coincide with the SERS results.2. The adsorption and film formation behavior together with the concentration effect on the inhibition of BIMH were investigated by electrochemical SERS in non-aqueous solution. With the increase of concentration of BIMH, the inhibition of BIMH showed the high efficiency, and followed with the decrease in inhibition with the further increase of concentration. In the present concentration range, the BMIH solution with 0.01 M exhibited the highest efficient inhibition for Cu surface.3. The adsorption behavior of BIMH with different concentration on Ni surface was studied by in-situ SERS combined with electrochemical technique. Based on SERS and electrochemical results, the inhibition efficiency was increased with the increase of concentration in certain range.