The Adsorption of Urea on Polycrystalline Gold Electrodes
Date
2016-09-21
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0003-0440-083X
Type
Thesis
Degree Level
Masters
Abstract
The adsorption of urea on Au polycrystalline electrodes was investigated using infrared spectroscopy, surface-enhanced infrared absorption (SEIRA) spectroscopy, electrochemistry, and spectroelectrochemistry. Electrochemical investigation indicates urea adsorption on a polycrystalline Au electrode at neutral pH as long as the surface is not oxidized. Partial urea desorption occurs at 0.5 V vs Ag/AgCl and above 0.8 V vs Ag/AgCl Au oxidation occurs, desorbing the remaining urea. Adsorption modes of urea were studied using SEIRA spectroscopy. Urea can adsorb in one of three configurations; through both nitrogen atoms (I), through a single nitrogen atom (II), or through the oxygen atom (III). In H2O, adsorption occurs through both nitrogen atoms (I) and through a single nitrogen atom (II). For experiments in D2O adsorption occurs through both nitrogen atoms (II) and through the oxygen atom (III). The behavior of these adsorbates as a function of potential was studied using spectroelectrochemsitry, where an electrochemical cell with a Au coated IR window at the base is mounted on a benchtop spectrometer and the adsorbates at the surface are investigated as the applied potential is varied. In H2O, at potentials
of 0.9 V all of II has desorbed while some of I remains. In D2O experiments, at potentials of 0.9 V all of III has desorbed while some of I remains. Adsorption studies of various possible breakdown products of urea indicates that no known product is being formed.
Description
Keywords
Urea, SEIRAS, Gold, Infrared Spectroscopy, Adsorption
Citation
Degree
Master of Science (M.Sc.)
Department
Chemistry
Program
Chemistry
Advisor
Burgess, Ian J