| All the research work presented here includes electrochemical and Raman spectroscopic studies with some important biomolecules and organic molecules and these studies are based on gold nanoparticle arrays modified on some specific conductive substrates. Specifically, gold nanoparticles, which were prepared by electroplating or wet chemical reduction method in this research work and possess good performance for electrochemical catalysis and localized surface plasmon resonance(LSPR) effect, were used in the study of electrochemical detection, electrochemical catalysis and surface-enhanced Raman spectroscopy. The main research works are as follows:(1) Epinephrine, as a kind of neurotransmitter in human blood, plays an irreplaceable role in human central nervous system. Ascorbic acid(AA) is an indispensable substance in human body which has a great significance on normal operation of various human body functions. The lack of ascorbic acid can cause many diseases such as scurvy. Because of their similar oxidation potential, simultaneous detection of epinephrine and ascorbic acid can be done only after the working electrode is modified and functionalized previously. In this work, the concomitant epinephrine and ascorbic acid were analyzed by using the goldnanoparticles-modified electrodes prepared by cyclic voltammetry(CV), i-t curve or chronoamperometry-CV technique respectively. The results obtained show that the gold- nanoparticles-modified electrodes prepared by CV or i-t curve were not so ideal as for their analytical performance. Relatively, the gold-nanoparticles-modified electrode prepared by chronoamperometry-CV method can meet the demand of electrochemical detection of epinephrine and ascorbic acid at the same time. Moreover, both the peak current densities of epinephrine and ascorbic acid have good linear relationships with their concentrations within a certain range.(2) Methanol is an important resource for direct fuel cell research because of its advantages such as simple molecular structure, easy to get, safety for storage and transportation. Platinum is widely used as catalytic material for its unique electrocatalytic ability with methanol oxidation. But the intermediate, CO, generated in methanol oxidation process can make the platinum poisoning and its catalytic activity decreasing. However the existence of gold can make the poisoned platinum catalyst regenerate. Pt/Au NPs/ITO electrode was made by electrodepositing of platinum on a gold- nanoparticles-modified ITO electrode. Electrocatalytic oxidation reactions of methanol on the as-prepared platinum coating gold-nanoparticlesmodified ITO electrode were carried out. The electrodepositing parameters were optimized and the good electrocatalytic performance of the Pt/Au NPs/ITO electrode obtained here is better than the Au NPs/ITO electrode without platinum. The as-prepared Pt/Au NPs/ITO electrode has good ability to resist poisoning, stable electrocatalytic oxidation performance.(3) With the development of nanomaterials, surface-enhanced Raman scattering(SERS) spectroscopy has become a powerful tool for molecular spectroscopic information acquisition now. SERS technique has many advantages over other analytical techniques, such as nondestructive testing, aqueous solution analysis, simple sample preparation and high sensitivity and so on. In this part of my research work, chronoamperometry was first used to fabricate gold nanoparticle seeds on ITO, and then wet chemical reduction was used to enlarge gold nanoparticle seeds to an appropriate size. Nanoparticles with different size could be obtained through the control of the growth time. PATP was used as a probe molecule to characterize the SERS activity of the obtained substrates. Raman characteristic frequencies of PATP, PATP-Au3 and DMAB-Au3 were calculated based on density functional theory(DFT). By analysis with the experimental and theoretical spectroscopic information, it was demonstrated that a conversion from PATP to DMAB happened in the SERS measurement. |
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