Direct‐Current Plasma Formation Between Two Liquid Water Surfaces

ABSTRACT Non‐thermal, atmospheric‐pressure plasmas formed near liquids are typically in contact with metal at a boundary. Here, a new strategy is presented to generate a direct current (DC) plasma between a pair of liquid water surfaces. Characterization of the system shows that remarkably, plasma properties such as gas temperature and electron density remain constant over a wide current range. Concomitantly, this new reactor geometry was found to avoid a glow‐to‐arc transition at the highest currents studied. The reactor was applied to the degradation of phenol and found to achieve up to 90% removal in 60 min. The ability to sustain a high‐power DC plasma in direct contact with only liquid water is attractive for scalable applications in chemical synthesis and pollutant degradation.