Observation of currentless redox reactions on surface of water jet immersed in low-pressure plasma

Abstract

We investigated oxidation-reduction reactions on the surface of water jet immersed in a low-pressure inductively coupled helium plasma. The electrical potential of the water jet was floating, and no electrical current was supplied from the plasma to the water jet. We observed the productions of molecular hydrogen and molecular oxygen. We also observed negligible consumption of water vapor in the gas phase, suggesting that the productions of hydrogen and oxygen were not owing to the conversion from water vapor. When we employed silver nitrate solution instead of pure water, we observed the decrease in the production rate of hydrogen, whereas the production rate of oxygen was the same in pure water and silver nitrate solution. In addition, we found the synthesis of silver particulates in the silver nitrate solution, indicating the competition between the reductions of H+ and Ag+. Thus, the experimental results reveal the simultaneous oxidation and reduction at the same plasma-liquid interface.

Production rates and destruction frequencies of ammonia in inductively coupled H2O/N2 and H2/N2 plasmas

“…The evacuation speed for water vapor was enhanced by installing traps at the temperature of liquid nitrogen in the vacuum chamber. [ 26 ] Liquid water was stored in a vessel connected to the vacuum chamber, and water vapor was obtained by the natural evaporation of liquid water. The flow rate of water vapor, which was controlled using a needle valve, was estimated to be 106 sccm.…”

“…The flow rate of water vapor, which was controlled using a needle valve, was estimated to be 106 sccm. [ 26 ] The partial pressure of water vapor, which was measured using a capacitance manometer, was 2 mTorr. Molecular nitrogen was added to water vapor to realize a total pressure of 12 mTorr.…”

Detection of hydrated electrons in water-jet immersed in low-pressure plasma by laser-induced desolvation

“…To overcome the difficulty, in the present work, we injected a micrometer-size water jet into a low-pressure inductively coupled plasma [19,20]. The plasma potential is determined by the potential of the chamber wall in the inductively coupled plasma source, and the potential difference between the plasma and the water jet is controllable by the bias voltage applied to the water jet.…”

Silver Nanoparticle Synthesis in Glycerol by Low-Pressure Plasma-Driven Electrolysis: The Roles of Free Electrons and Photons

“…Interestingly, the comparatively high pressure in our experiment (5 Torr) enables in-flight water treatment at room temperature, without the use of a liquid nitrogen coldtrap to prevent rapid evaporation, as was done in previous work. 46,47 However, Ag + reduction in the aqueous solution does not exhibit such a dependence on 5 eV photons, as illustrated in section S1 of the Supporting Information.…”