The air-water interface of condensed water microdroplets does not produce H$_2$O$_2$

Nayara H. Musskopf; Adair Gallo; Peng Zhang; Jeferson Petry; Himanshu Mishra

paper

The air-water interface of condensed water microdroplets does not produce H $_{2}$ O $_{2}$

arXiv:2109.03096

Abstract

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 speculated to be ultrahigh electric fields at the air-water interface; smaller droplets present higher interfacial area and produce higher (detectable) H $_{2}$ O $_{2}$ yields. Herein, we present an alternative explanation for these experimental observations. We compare H $_{2}$ O $_{2}$ production in water microdroplets condensed from vapor produced via (i) heating water to 50-70 °C and (ii) ultrasonic humidification (as exploited in the original report). Water microdroplets condensed after heating do not show any enhancement in the H $_{2}$ O $_{2}$ level in comparison to the bulk water, regardless of droplet size or the substrate wettability. In contrast, those condensed after ultrasonic humidification produce significantly higher H $_{2}$ O $_{2}$ quantities. We conclude that the ultrasonication of water contributes to the H $_{2}$ O $_{2}$ production, not droplet interfacial effects.

The air-water interface of condensed water microdroplets does not produce H2​O2​

Abstract

The air-water interface of condensed water microdroplets does not produce H $_{2}$ O $_{2}$