I would like to know if it is possible to generate hydrogen peroxide in the atmospheric air with UV-Light or if some catalyzer is needed for that.
If affirmative, is there a specific UV wavelength that is the peak of H2O2 generation?
Thank you
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3$\begingroup$ What's the source of hydrogen? The air consists of about 0.00005 % of hydrogen, and of approx. 4 % water at best. It would also be helpful to understand what this $\ce{H2O2}$ generation would be useful for. $\endgroup$– andselisk ♦Commented Oct 6, 2022 at 12:23
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1$\begingroup$ @andselisk the reaction would be by the moisture in the air and oxygen, the idea is to use hydrogen peroxide as a disinfectant such as this product: rgf.com/products/phi-air-purification/… $\endgroup$– GeisterfahrerCommented Oct 6, 2022 at 13:46
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1$\begingroup$ These products are of no use. $\endgroup$– ACRCommented Oct 6, 2022 at 15:29
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Hydrogen peroxide is surprisingly ubiquituous in the atmosphere, all you need is trace or ultratrace analytical methods. Rain water has a measurable amount of it. This is not due to pollution. It is Nature's composition of rainwater. There must be a purpose just like trace nitric acid in rain water serves as a plant fertilizer. Recently, research at Stanford showed that if pure water is misted in air, measurable quantities of $\ce{H2O2}$ are formed in the mist. Even more surprising fact is that no UV light is needed. Misting water in air in complete darkness also generates $\ce{H2O2}$.
In short, no catalyst or light is needed. All you need is a very fine mist of water being sprayed in the air and you will have a small but measurable concentration $\ce{H2O2}$ in the mist. The phenomenon is not well-understood but there are only conjectures so far for this reproducible experiment. The authors had been studying this for several years.
Further reading: Lee, J.K., Walker, K.L., Han, H.S., Kang, J., Prinz, F.B., Waymouth, R.M., Nam, H.G. and Zare, R.N., 2019. Spontaneous generation of hydrogen peroxide from aqueous microdroplets. Proceedings of the National Academy of Sciences, 116(39), pp.19294-19298.
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$\begingroup$ Nothing spontaneous about it; the atomization forms static electricity, think thunderstorm. here is their comment "In what follows, we report the direct, spontaneous generation of H2O2 from aqueous microdroplets in the absence of applied voltage, catalyst, or any other added chemicals. We also speculate about the nature of the mechanism responsible for these observations." I get upset when a proper energy balance is ignored; someone has to squeeze the rubber bulb. The chemistry is exciting tho. $\endgroup$– jimchmstCommented Oct 6, 2022 at 21:31
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$\begingroup$ I must apologize for using spontaneous in the vernacular sense because the production of the peroxide is spontaneous in the thermodynamic sense, otherwise it would not form. The energy supplied from imposed KE in the atomization overcomes the probably positive entropy change of a system far from equilibrium since there was no peroxide to start. All that is needed is a possible mechanism and the micro surfaces seem to provide that. Static electricity can be formidable albeit difficult to control and direct. $\endgroup$– jimchmstCommented Oct 8, 2022 at 22:42