Efficient and Selectable Production of Reactive Species Using a Nanosecond Pulsed Discharge in Gas Bubbles in Liquid

A plasma gas bubble-in-liquid method for high production of selectable reactive species using a nanosecond pulse generator has been developed. The gas of choice is fed through a hollow needle in a point-to-plate bubble discharge, enabling improved selection of reactive species. The increased interface reactions, between the gas-plasma and water through bubbles, give higher productivity. H₂O₂ was the predominant species produced using Ar plasma, while predominantly NO3- and NO₂ were generated using air plasma, in good agreement with the observed emission spectra. This method has nearly 100% selectivity for H₂O₂, with seven times higher production, and 92% selectivity for NO3-, with nearly twice the production, compared with a plasma above the water. A plasma gas bubble-in-liquid, with chosen gas, method is described. The gas of choice enables improved selection of reactive species and increased interface reactions enable higher productivity. "Ar" plasma produces a high concentration of H₂O₂, while "air" plasma produces high concentrations ofNO3- and NO₂. The selectivity and productivity are much higher than with a plasma created above liquid.