Joule
Volume 3, Issue 12, 18 December 2019, Pages 2942-2954
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Article
Electrosynthesis of Hydrogen Peroxide by Phase-Transfer Catalysis

https://doi.org/10.1016/j.joule.2019.09.019Get rights and content
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Highlights

  • Phase-transfer catalysis shuttles redox equivalents from the site of electrolysis

  • Organic electrocatalysis is used to generate H2O2, a high-value liquid product

  • Hydrogen peroxide is produced in electrolyte-free media, avoiding separation steps

  • A flow device demonstrates long-term operation at high faradic efficiencies

Context & Scale

Hydrogen peroxide (H2O2) is a crucial oxidant for processes as diverse as wood pulping, fine chemical synthesis, water purification, and environmental remediation. Legacy production of peroxide relies on fossil resources and is difficult to downscale. Renewable electricity can be used to drive the electrochemical synthesis of H2O2 directly from H2O and O2, but current electrochemical methods suffer from the use of precious metals, toxic catalyst materials, and the requirement of expensive downstream separation of H2O2 from the electrolyte. We address all of these challenges by coupling electrochemistry with phase-transfer catalysis using organic quinone mediators to furnish continuous H2O2 synthesis and separation.

Summary

The portable electrochemical generation of hydrogen peroxide (H2O2) 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.

Keywords

hydrogen peroxide
flow electrochemistry
phase transfer
anthraquinones
water treatment

Cited by (0)

3

These authors contributed equally

4

Present address: School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK

5

Lead Contact