A Simple Liquid-Liquid Biphasic System for Hydrogen Peroxide Generation

Although electron transfer reactions at liquid liquid interfaces have been thoroughly studied in the presence of deliberately added potential determining ions or phase transfer catalysts, little is known about these reactions in the absence of the above species. Here, we report the formation of hydrogen peroxide (H2O2) in a liquid liquid two-phase system with only an electron donor (decamethylferrocene) solution in trifluorotoluene (TFT) and a proton donor solution (HClO4) in water. To detect H2O2, we used fluorescent microscopy and scanning electrochemical microscopy (SECM). We applied a potential sweep program to the SECM probe to overcome the electrode deactivation. To provide insight into the reaction rate and mechanism, we fitted SECM results to finite elements simulations. From the results of UV vis spectroscopy, we determined a H2O2 partition coefficient of 0.03 and the standard Gibbs energy of H2O2 transfer from water to TFT as 9.5 kJ/mol. The most important conclusion from this work is that the studied system provides conditions for spontaneous transfer of protons from the aqueous to the organic phase, even in the absence of deliberately added potential determining ions or phase transfer catalysts.