Objective: The overarching goal of this project is the development of nanometer-wide electrochemical cells for the purpose of performing single molecule electrochemical measurements. Coupled with these measurements will be the ability to measure fast heterogeneous electron transfer reaction rates.
Single molecule detection represents an important focus of current analytical chemistry as it affords the discovery and measurement of physical phenomena that are often masked when making ensemble measurements. Single molecule detection also allows characterization of individual molecular signals -and their response to changes in the local environment - over sub-nanometer length scales. Applications of these molecule (and environment-specific) responses in chemical sensing promises the ultimate in terms of sensitivity and selectivity in areas such as trace chemical analysis and single protein measurements.
The ability to perform single-molecule electrochemistry would be of significant scientific value. Specifically, an understanding electrochemical phenomena at the single molecule level will lead to a better fundamental understanding of standard half reaction potentials and free energies, diffusion coefficients and kinetic parameters such as rapid heterogeneous interfacial electron transfer rates; a current electroanalytical challenge. Moreover, fundamental studies of the effects of molecular environments on these phenomena could, more broadly, lead to improved sensors and molecular electronics. In this project, we are developing a novel, microfabricated, nanometer-wide electrochemical cell in which two electrodes are separated by gaps as small as 10 nm. The cells will be used to measure rapid heterogeneous electron transfer rates as well as the effects of molecular environment on these rates at the single molecule level. This research should provide a general platform for single molecule electrochemistry that can be applied to not only fundamental electrochemical studies, but to improved chemical detection and materials characterization at the nanoscale interface as well.