Water droplets, H2O2, electric fields, solvation, e−aq, and H2O•+

For the “spontaneous” formation of H2O2 in small droplets of H2O, 3 hypotheses have been proposed. 1. At the gas–water interface an electric field oxidizes HO− or H2O to HO•. 2. H2O comproportionates to H2O•+ (→HO• + H+) and H2O•− (e−aq). 3. At the the gas–water interface H+ and HO− are partially dehydrated, allowing formation of HO• and H•. 2 HO• produce H2O2. I show (1) that the postulated electric fields are not strong enough, and would oxidize H2O2, (2) that comproportionation is endergonic by 922 kJ/mol, and (3), that the cost of dehydration has not been taken into account. Instead, experimental setups cause formation of H2O2: sonication, contact between a metal surface and an O2-containing solution, and triboelectricity produce HO•, O2•−, and e−aq. Regarding the ultra-short-lived species H2O•+: E°(H2O•+/H2O) = +4.9±0.1 V and ΔfG°(H2O•+aq) = +(2.4±0.1)•102 kJ/mol.