Reproducible Contact Angles on Reproducible Metal Surfaces. II. Interfacial Contact Angles between Water and Organic Liquids on Surfaces of Silver and Gold

1942 ◽  
Vol 64 (7) ◽  
pp. 1530-1534 ◽  
Author(s):  
F. E. Bartell ◽  
Paul H. Cardwell
Keyword(s):  
Metal Surfaces ◽  
Contact Angles ◽  
Organic Liquids ◽  
Interfacial Contact

scholarly journals Structure, Dynamics, and Wettability of Water at Metal Interfaces

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Suji Gim ◽  
Kang Jin Cho ◽  
Hyung-Kyu Lim ◽  
Hyungjun Kim
Keyword(s):  
Surface Science ◽  
Metal Surfaces ◽  
Molecular Level ◽  
Contact Angles ◽  
Ambient Conditions ◽  
Metal Interface ◽  
Energy Applications ◽  
Structural Details ◽  
Water Metal ◽  
Metal Interfaces

Abstract The water/metal interface often governs important chemophysical processes in various technologies. Therefore, from scientific and engineering perspectives, the detailed molecular-level elucidation of the water/metal interface is of high priority, but the related research is limited. In experiments, the surface-science techniques, which can provide full structural details of the surface, are not easy to directly apply to the interfacial systems under ambient conditions, and the well-defined facets cannot be entirely free from contamination at the contact with water. To answer long-standing debates regarding the wettability, structure, and dynamics of water at metal interfaces, we here develop reliable first-principles-based multiscale simulations. Using the state-of-the-art simulations, we find that the clean metal surfaces are actually superhydrophilic and yield zero contact angles. Furthermore, we disclose an inadequacy of widespread ice-like bilayer model of the water adlayers on metal surfaces from both averaged structural and dynamic points of view. Our findings on the nature of water on metal surfaces provide new molecular level perspectives on the tuning and design of water/metal interfaces that are at the heart of many energy applications.

scholarly journals Flooded by Success: On the Role of Electrode Wettability in CO2 Electrolyzers That Generate Liquid Products

2020 ◽  
Author(s):  
McLain Leonard ◽  
Michael Orella ◽  
Nick Aiello ◽  
Yuriy Román-Leshkov ◽  
Antoni Forner-Cuenca ◽  
...  
Keyword(s):  
Formic Acid ◽  
Flow Rate ◽  
Gas Diffusion ◽  
Contact Angles ◽  
Ex Situ ◽  
Organic Liquids ◽  
Stable Operation ◽  
Acid Product ◽  
Wide Range ◽  
Liquid Products

The economic operation of carbon dioxide (CO2) electrolyzers generating liquid products will likely require high reactant conversions and high product concentrations, conditions anticipated to challenge existing gas diffusion electrodes (GDEs). Notably, electrode wettability will increase as lower surface tension products (e.g., formic acid, methanol, ethanol, and 1-propanol) are introduced into flowing electrolyte streams potentially leading to flooding. To better understand the hydraulically stable electrolyzer operating envelopes in mixed aqueous-organic liquid domains, we connect intrinsic porous electrode wettability descriptors to system operating parameters such as electrolyte flow rate and applied current. Specifically, we first measure contact angles of various water-organic dilutions on polytetrafluoroethylene (PTFE) and graphite surfaces as ex situ planar analogues for the major GDE components. We then use material balances around the reactive gas-liquid interface, to calculate product mass fractions as a function of liquid water sweep rate (water source and diluent) and the total current. Product composition maps enable visualization of the extent to which changes in cell performance can lead to changes in capillary pressure, a crucial determinant of GDE saturation. These analyses reveal that formic acid product mixtures pose little risk for GDE flooding across a wide range of flow rate and current combinations, but that effluents enriched with less than 30% alcohols content by mass may cause flooding. This study provides initial guidance into estimating flooding conditions for PTFE-based GDEs in contact with organic-enriched streams and indicates opportunities for oleophobic surface treatments that repel aqueous and organic liquids, expanding regions of stable operation<br>

scholarly journals Flooded by Success: On the Role of Electrode Wettability in CO2 Electrolyzers That Generate Liquid Products

2020 ◽  
Author(s):  
McLain Leonard ◽  
Michael Orella ◽  
Nick Aiello ◽  
Antoni Forner-Cuenca ◽  
Yuriy Román-Leshkov ◽  
...  
Keyword(s):  
Formic Acid ◽  
Flow Rate ◽  
Gas Diffusion ◽  
Contact Angles ◽  
Ex Situ ◽  
Organic Liquids ◽  
Stable Operation ◽  
Acid Product ◽  
Wide Range ◽  
Liquid Products

The economic operation of carbon dioxide (CO2) electrolyzers generating liquid products will likely require high reactant conversions and high product concentrations, conditions anticipated to challenge existing gas diffusion electrodes (GDEs). Notably, electrode wettability will increase as lower surface tension products (e.g., formic acid, methanol, ethanol, and 1-propanol) are introduced into flowing electrolyte streams potentially leading to flooding. To better understand the hydraulically stable electrolyzer operating envelopes in mixed aqueous-organic liquid domains, we connect intrinsic porous electrode wettability descriptors to system operating parameters such as electrolyte flow rate and applied current. Specifically, we first measure contact angles of various water-organic dilutions on polytetrafluoroethylene (PTFE) and graphite surfaces as ex situ planar analogues for the major GDE components. We then use material balances around the reactive gas-liquid interface, to calculate product mass fractions as a function of liquid water sweep rate (water source and diluent) and the total current. Product composition maps enable visualization of the extent to which changes in cell performance can lead to changes in capillary pressure, a crucial determinant of GDE saturation. These analyses reveal that formic acid product mixtures pose little risk for GDE flooding across a wide range of flow rate and current combinations, but that effluents enriched with less than 30% alcohols content by mass may cause flooding. This study provides initial guidance into estimating flooding conditions for PTFE-based GDEs in contact with organic-enriched streams and indicates opportunities for oleophobic surface treatments that repel aqueous and organic liquids, expanding regions of stable operation<br>

Candle Soot as a Template for a Transparent Robust Superamphiphobic Coating

Science ◽  
2011 ◽  
Vol 335 (6064) ◽  
pp. 67-70 ◽  
Author(s):  
Xu Deng ◽  
Lena Mammen ◽  
Hans-Jürgen Butt ◽  
Doris Vollmer
Keyword(s):  
Contact Angles ◽  
Silica Shell ◽  
Low Energy ◽  
Organic Liquids ◽  
Essential Step ◽  
Candle Soot ◽  
Superhydrophobic Coatings ◽  
Black Coating ◽  
Properties Of Materials ◽  
Energy Surfaces

Coating is an essential step in adjusting the surface properties of materials. Superhydrophobic coatings with contact angles greater than 150° and roll-off angles below 10° for water have been developed, based on low-energy surfaces and roughness on the nano- and micrometer scales. However, these surfaces are still wetted by organic liquids such as surfactant-based solutions, alcohols, or alkanes. Coatings that are simultaneously superhydrophobic and superoleophobic are rare. We designed an easily fabricated, transparent, and oil-rebounding superamphiphobic coating. A porous deposit of candle soot was coated with a 25-nanometer-thick silica shell. The black coating became transparent after calcination at 600°C. After silanization, the coating was superamphiphobic and remained so even after its top layer was damaged by sand impingement.

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