APPLICATION OF THE POLARIZATION MODEL TO ELECTROCHEMICAL INTERFACES.

Open Access
- Author:
- Boland, Erin Katherine
- Graduate Program:
- Chemical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 03, 2010
- Committee Members:
- Janna Kay Maranas, Thesis Advisor/Co-Advisor
Janna Kay Maranas, Thesis Advisor/Co-Advisor - Keywords:
- molecular dynamics simulation
electrochemical interface - Abstract:
- Fuel cells represent an appealing improvement for energy conversion in transportation applications, offering better fuel economy and lower emissions. In order for the wide scale adoption of this technology to occur, specific performance measurements: fuel efficiency, power output and cost must be met. Despite engineering efforts, a device which meets all performance metrics simultaneously has not yet been developed. Although scientific effort has attempted to improve designs, a fundamental understanding of the molecular scale phenomena driving fuel cell performance is lacking, largely due to the fact that the electrified interface cannot be isolated experimentally. Molecular simulation offers the opportunity to study this interface, however few easily implementable models which capture the desired physical phenomena of the electrochemical interface exist. This thesis integrates existing models into a single force field appropriate for molecular dynamics simulation. The thesis begins by examining the Polarization Model and adapting it for use with periodic boundary conditions. The model is found to predict over-structured water and glass-like dynamics (very slow diffusion). The Polarization Model is examined and altered as a means of examining the underlying cause of the slow dynamics. The representation water interactions with a metal interface are examined using both a non-polarizable and a polarizable water model, providing the necessary adaption of the surface model for use with polarizable electrolyte. The final portion of this thesis examines the representation of sulfuric acid and identifies the shortcomings of simple representations of molecular interactions, developing recommendations for further model extensions.