Electrochemical Monitoring of the Formation of Self Organized Monolayers: Octadecylphosphonic Acid on Anodically Grown Titanium Dioxide

Abstract

The formation of a self assembled monolayer (SAM) on anodic titanium dioxide was monitored by impedance spectroscopy and compared to results from X-ray photoelectron spectroscopy (XPS). Results provide information on the formation kinetics of an n-octadecylphosphonic acid monolayer and its stability against UV-irradiation. The results reveal typical adsorbtion characteristics of the monolayer depending on the immersion time and the immersion concentration, respectively. The XPS results show a strong stability of the bond between the phosphonic acid anchor group and the TiO₂ surface under UV-irradiation. The phosphate rest remains on the surface while the carbonic rest of the molecule is decomposed.