An interdisciplinary collaboration between researchers at Case Western Reserve University and the University of Notre Dame has revealed a critical interaction that is occurring at this plasma-liquid interface in that the electrons in plasma actually serve to separate water, producing hydrogen gas.
In a paper set to appear as a Fast Track Communication in the Journal of Physics D: Applied Physics, David B. Go, assistant professor of aerospace and mechanical engineering at the University of Notre Dame, and his graduate student Paul Rumbach teamed with R. Mohan Sankaran, associate professor of chemical engineering at Case Western Reserve, and his undergraduate student Megan Witzke describe a series of experiments that revealed this new chemistry.
A plasma is an ionized gas, consisting of not only neutral gas molecules but also free electrons and charged ions. Though often thought of as very hot, microplasmas are a unique regime of plasmas that can be formed at atmospheric pressure and are considered "cold plasmas" because they are typically around room temperature. In most plasma-liquid studies, the focus has been on how the different gas species and photons (light) produced by the plasma interact with the liquid.
"Many researchers have revealed that reactive oxygen and nitrogen species in the plasma play an important role in the plasma-liquid interaction," Sankaran said, "But we've always thought that the electrons must be playing an important part. We had preliminary evidence that suggested that the plasma electrons would reduce various chemical species in the liquid but always believed that they must have been interacting with water as well. This study conclusively proves that the electrons directly interact with and electrolyze water."
Water electrolysis is the splitting of water into oxygen and hydrogen and usually occurs in an electrochemical cell with two metals electrodes. In their work Go and Sankaran replaced one of the metal electrodes with an atmospheric-pressure plasma jet. However, the result was that the plasma electrochemical cell acted like a traditional electrochemical cell.
"We found that at the plasma-liquid interface, the plasma formed a virtual cathode and electrons from the plasma reduced hydrogen ions to produce hydrogen gas while at the metal anode, oxidation formed oxygen gas. The reactions are the same as for a traditional electrochemical cell, except now the plasma jet plays the role of one of the electrodes," Go said.
While Go and Sankaran acknowledge that the plasma-liquid interaction is an incredibly complex phenomenon, they agree that this work fills in a crucial piece of the puzzle."As we continue to develop plasma jets for all kinds of applications, be they medical, environmental or for synthesizing materials," Go said. "It's crucial that we understand the fundamental chemistry that is occurring. The role of electrons has been somewhat overlooked, but we show that they play an important role and must be considered as we continue to try to understand these new microplasma devices."
David Go | EurekAlert!
Observations of nearby supernova and associated jet cocoon provide new insights on gamma-ray bursts
18.01.2019 | George Washington University
A new twist on a mesmerizing story
17.01.2019 | ETH Zurich Department of Physics
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
18.01.2019 | Materials Sciences
18.01.2019 | Life Sciences
18.01.2019 | Health and Medicine