Recent reports on the formation of hydrogen peroxide (H2O2) in water microdroplets produced via pneumatic spraying or capillary condensation have garnered significant attention. How covalent bonds in water could break...

Recent reports on the production of hydrogen peroxide (H 2 O 2 ) on the surface of condensed water microdroplets without the addition of catalysts or additives have sparked significant interest. The underlying mechanism is thought to be ultrahigh electric fields at the air−water interface; smaller droplets present larger interfacial areas and produce higher (detectable) H 2 O 2 yields. To gain insights into this phenomenon, we performed condensation experiments and quantified H 2 O 2 formation as a function of the vapor source. Specifically, we compared the H 2 O 2 concentration in water microdroplets condensed from the vapor realized via (i) heating water in the range of 50−70 °C and (ii) ultrasonic humidification (as exploited in the original report). Experimental results revealed that the H 2 O 2 level inside water microdroplets condensed via heating water was below our detection limit (≥0.25 μM), regardless of the droplet size or the substrate wettability. In contrast, water droplets condensed via ultrasonic humidification contained significantly higher (∼1 μM) H 2 O 2 concentrations. We conclude that the ultrasonic humidifiers contribute to H 2 O 2 production, not droplet interfacial effects.

No abstract

No abstract