Enhanced Sensor Capability of Juxtaposed β-Cyclodextrin Rings in TiO2 Ultrathin Matrix as Determined by Cyclic Surface-Polarization Impedance Measurement

doi:10.18494/sam.2008.535

Abstract

Highlights

IntroductionSolid metal electrodes in water is given by the “frequency-dependent” capacitance rather than the “ideal” capacitance
Sensors and Materials, Vol 20, No 4 (2008)solid metal electrodes in water is given by the “frequency-dependent” capacitance rather than the “ideal” capacitance
The Pt electrodes were modified with three different types of self-assembled monolayer (SAM), namely, -OH, -COOH, and -pyridine terminal groups using 2-mercaptoethanol, 3-mercaptopropionic acid, and 4,4 ́-dithiodipyridine, respectively

Summary

Introduction

Solid metal electrodes in water is given by the “frequency-dependent” capacitance rather than the “ideal” capacitance. This behavior is usually called “capacitance dispersion” or a constant phase element (CPE).(4,5) The electrode surface is not ideal and has atomicscale heterogeneity such as “surface disorder” and specific anion adsorption.[6,7]. CPE impedance depends on the adsorption and desorption of chemical substances to and from the electrode surface, respectively. The adsorption and desorption of chemical substances can be detected by measuring the electrochemical impedance under a dynamically controlled electrode potential. Impedance changes due to an electrode potential change represent chemical sensor outputs, and a broad range of chemical substances can be identified from the CPE impedance-voltage curve obtained by the cSPI method. We have successfully applied this technique to the convenient detection of the proton transfer of hydroxyl aromatic compounds trapped in cyclodextrin cavities

Experimental

Results and Discussion

Conclusion