Characterization of electric double layer structure at electrode/water interface

Solid/water interface widely exists in a variety of systems, including electrochemical cell, bio membrane, and minerals. It is evidenced that the interfacial water structure has an important impact on the properties and functioning of these systems. However, due to the confined scale of interfacial water structure and limitation of previous characterization techniques, a thorough understanding of the behavior of water molecules at these interfaces was not obtained. This dissertation presents and discusses the application and characterization of electrode/water interface in electrochemical systems. The application of a topological insulator, Bi2Te3, in electrochemical sensing was evaluated, where it was found to have outstanding performance for the measurement of H2O2 in aqueous solution environments, in terms of sensitivity, detection limit, and selectivity. And its electrochemical performance was analyzed by microkinetic analysis. Low charge transfer resistance was identified at the surface of Bi2Te3, which matches with its high surface conductivity property. To achieve in-situ characterization of electrode/water interface, we developed and utilized two techniques: electrochemical three-dimensional atomic force microscopy (EC-3D-AFM) and electrochemical shell isolated nanoparticle enhanced Raman spectroscopy (EC-SHINERS) to study the potential dependent evolution of interfacial water structure on graphite/water interface. With their interfacial sensitivity, we identified a downward movement of the bottommost water layer towards the electrode surface at negative electric bias, accompanied by a weakened hydrogen bonding network around the electrode surface space. These observations are explained by a potential driven reorientation of water molecules and a synergistic effect from the hydrophobic electrode surface. A new configuration for enhanced Raman spectroscopy was also proposed and tested as a solution to the problems of the existing SHINERS technique. With these works, new approaches and insights can hopefully be brought to the study of solid/water interface. Electrified water-solid interface exists ubiquitously in nature and plays pivotal roles in biosensing, renewable energy, water filtration, and more. For more than a century, such interfacial structure remains elusive, and even the presence of water at the interface has been questioned. Here we resolve this long-standing puzzle. We experimentally observe that water-graphite interface consists of fluctuating amounts of hydrocarbons that are subject to electrochemical removal, and the interfacial water structure is dependent on both the intrinsic electric field and the amount of extrinsic hydrocarbons. These results will be critical for the understanding and design of all the realistic systems that rely on interfacial water.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Materials Science & Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Zhao, Fujia

Contributors dc:contributor

• Zhang, Yingjie
• Gewirth, Andrew
• Shim, Moonsub
• Perry, Nicola

• Atomic Force Microscopy
• Electrochemical Interface
• Raman Spectroscopy

Statement dc:rights

• Copyright 2024 Fujia Zhao

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127500

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127500