Electrochemistry and Physics of Nanobubbles
Abstract
ABSTRACT: This proposal describes a continuation of our previous 3-year program that focuses on understanding the electrochemistry and physics of electron-transfer at three-phase contact lines and fundamental aspects of electrochemical nucleation of gas phases. During the past 3 years, we have developed electrochemical methods for investigating the nucleation, structure, andthermodynamics of individual nanobubbles of O2, N2, H2, and CO2 using nanoelectrode methods developed in our laboratory. Our investigations represent the first observations of electrochemical formation of a gas phases on nanoscale dimensions (5 ~ 100 nm) that yield stable nanobubbles. We have reported investigations of different aspects of the thermodynamics and nucleation of gas phase, including first reported measurements of: the critical size of nuclei (~50 gas molecules at ~250 atm), the surface tension of sub-10 nm nanobubbles, and the potential dependent rate of nucleation. These results represent significant contributions to understanding gas nucleation inelectrochemistry. Gas is the product of many important electrocatalytic processes, including H2 and O2 production from water splitting, and CO2 generation in many hydrocarbon fuel cells. Unwanted gas formation occurs also as deleterious reactions in energy storage systems; the formation of gasnanobubbles on electrode surfaces hinders the transport of reactant species to reactive sites, creating an additional overpotential, lowering efficiency, and can lead to hazardous conditions. Thus a detailed quantitative description of the behavior of nanobubbles at electrode surfaces, especially a quantitative description of their formation, is critical as the underpinnings in improving electrode materials, electrocatalytic rates, and safety. The proposed work described herein, will have long-term impact on developing methods and conditions to improve the stability and performance of electrochemical energy generation and storage, and applications of new high performance materials used, for instance, in biomedical devices and storage of corrosive materials.We propose studies of (i) the role of counter-ion adsorption on gas nucleation rates; (ii) the role of interfacial electric fields in creating conditions for the oscillatory nucleation and collapse of nanobubbles; (iii) spectroelectrochemical measurements of the three-phase gas/solid/liquid interface, and (iv) the stability of metal nanoparticles used in electrocatalysis under conditions of gas nucleation on their surface. Our proposed studies involve development of new experimental methods: construction of a high pressure electrochemical cell (1000 atm), construction of an electrochemically generated chemiluminescence imaging system and application of scanning electrochemical cell microscopy.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 23, 2019
- Source ID
- N000141912331
Entities
People
- Henry S. White
Organizations
- Office of Naval Research
- United States Navy
- University of Utah