Mechanism of Hydrogen Peroxide Formation on Sprayed Water Microdroplets

Hydrocarbon Degradation by Contact with Anoxic Water Microdroplets

“…The electrons can be accepted by H + ions to form •H. We also have the process occurring at the interface H + + OH – → •H + •OH, as proposed by Colussi . Hence, at the interface but not the bulk or the interior of the droplet, we have …”

“…We also have the process occurring at the interface H + + OH − → •H + •OH, as proposed by Colussi. 39 Hence, at the interface but not the bulk or the interior of the droplet, we have…”

“…The existence of electrons that come about accompanying the formation of •OH at the gas–water interface of the microdroplets has been supported by the unique reduction reaction over water microdroplets. ,,,− Formation of H 2 has been suggested to be the fate of the electrons pulled from the water microdroplet interface. , To verify the possible formation of H 2 at the water–oil microdroplet interface, we initially evacuate the fresh emulsion for 10 min, which can exclude interference from potentially dissolved H 2 in water (Figure a, see the materials for the detailed procedure). The absence of dissolved H 2 in the fresh evacuated emulsion was further confirmed by the molecular hydrogen test kit that can detect dissolved H 2 at ppb level (Movies S1 and S2).…”

Water Microdroplets-Initiated Methane Oxidation

“…There is compelling evidence that the hydroxyl radical can be formed in multiple ways in water microdroplets, particularly its air–water interface (AWI). One way is the direct transfer of single electron from the hydroxyl anion (OH – ) to generate the hydroxyl radical (OH – → OH· + e) facilitated by the strong electric field across the AWI (10 7 V/cm). − Another way involves single-electron transfer from the OH – to H + (H + + OH – → H· + OH·), which is reported as a thermodynamically favorable process in the AWI region (Δ H = −375 kJ mol –1 ) . Many spontaneous redox reactions across the AWI have been successfully observed during this process. − Furthermore, the charge transfer during contact electrification between the water–solid and water–gas interfaces also contribute to the abundant presence of OH·. , With aid of the generated OH· across the AWI, organic syntheses have been readily achieved by the radical-initiated C­(sp 3 )–H activation of toluene in the water microdroplets such its C–N coupling with amines and its C–C coupling with carbon dioxide. , …”

One-Step, Catalyst-Free Formation of Phenol from Benzoic Acid Using Water Microdroplets

“…Figure a shows the proposed mechanism of the formation of phenol from benzoic acid in water microdroplets, which was determined by using mass spectrometry. First, water is ionized at the air–water interface because of the strong electric field and contact electrification − (eq 1), followed by the formation of hydroxyl and hydrogen radicals (eq 2). Also, the hydroxyl radical formation from the hydroxide anion will be accelerated at the surface of a corona bubble .…”