Abstract
Abstract
Plasma-activated gas (PAG) provides a contact-free route for disinfecting structurally complex spaces and the surfaces of objects within them, yet its efficacy is limited by the slow gas–liquid conversion of long-lived precursors into the short-lived species that are the key to bacterial killing. Here we show that pre-spraying a non-bactericidal amount of H2O2 (100 μL, 0.1%) onto the target liquid reroutes the liquid-phase reaction chemistry of a closed-loop gliding-arc PAG system and shortens the time required to inactivate Staphylococcus aureus to the limit of detection from 10 to 7 min. Paired gas-phase and liquid-phase diagnostics, combined with a selective fluorescent probe, reveal that the pre-loaded H2O2 continuously intercepts newly formed NO2-, switching the system from a NO2--accumulating regime to an ONOOH-enhanced one and raising the ONOOH-related fluorescence signal—which reflects the amount of ONOOH generated in situ from the accumulated precursors—by over an order of magnitude (from 1.86 to 52.6 a.u.). Scavenger experiments identify ONOOH as the decisive bactericidal species, establishing active pre-loading as a generalizable strategy for steering plasma-driven reactive oxygen and nitrogen species chemistry. The residual nitrogen oxides are subsequently removed inside the closed loop by NaHCO3 gas washing, so that the treatment can be operated without releasing NOx.