Plasma-activated water (PAW) is a functionalized aqueous system in which multiple reactive oxygen and nitrogen species (RONS) are introduced through plasma-liquid interaction. Its biological effects largely depend on the composition and concentration of the reactive species, thereby conferring broad application potential. However, the generation, interfacial transport, and subsequent chemical evolution of RONS are strongly coupled with plasma discharge characteristics, gas-liquid mass transfer, and liquid-phase reactions, making it difficult to precisely regulate the composition of PAW and preserve its biological activity during storage.
This review systematically summarizes the recent advances in the generation, transport, and stabilization mechanisms of RONS in PAW. Particular emphasis is placed on: 1) strategies for regulating reactive species, with an in-depth analysis of gas-phase modulation (plasma parameters and operating conditions), interfacial regulation (gas-liquid mass transfer strategies), and liquid-phase control (physicochemical properties of the solution), which have been employed to enhance the production of reactive species and the biological activity of PAW; 2) studies on long-term stability are discussed, with emphasis on the effects of storage conditions (e.g. temperature and sealing conditions), additives, and preparation methods on PAW’s bio-activity. Furthermore, advances in plasma reactor design and large-scale PAW generation technologies are discussed with respect to production efficiency and practical applications.
Overall, the main strategies for regulating reactive species and improving the storage stability of PAW at the present stage are summarized, and future directions toward mechanism-guided design, efficient preparation, and practical applications of PAW are proposed.