Electrosynthesis of Hydrogen Peroxide by Phase Transfer Catalysis

The portable electrochemical generation of hydrogen peroxide from air and water would enable greater utilization of this versatile green oxidant in applications ranging from environmental remediation to portable sanitation. Currently, electrochemical H2O2 synthesis is hampered by the lack of low-cost, non-toxic catalysts that selectively reduce O2 to H2O2 and the lack of low-energy methods for separating the produced H2O2 from the electrolyte media. Herein, we show that a disulfonated anthraquinone can simultaneously catalyze the selective conversion of O2 to H2O2 and shuttle between immiscible aqueous and organic phases via ion exchange. We exploit both of these properties in a flow system to assemble an all Earth-abundant prototype device for the continuous generation and separation of H2O2 into an electrolyte-free water stream. The combination of molecular redox mediation and phase transfer catalysis demonstrated here has broad implications for the electrochemical synthesis and isolation of value-added chemicals and fuels.