Low-cell-voltage electrosynthesis of hydrogen peroxide

Abstract

The electrochemical oxygen reduction reaction (ORR) via a selective 2e⁻ pathway offers a great opportunity for the synthesis of H₂O₂ as an alternative to the traditional anthraquinone route. Unfortunately, the cell voltage of H₂O₂ electrosynthesis at neutral conditions still requires improvement to meet industrial demands, where high H₂O₂ productivity and low input energy are desired. Crucial impacts of each reactor component on the relationship of cell voltage and current density, and the over-potentials of each part of a flow cell reactor for H₂O₂ electrosynthesis are investigated in this research, which indicates that the overpotential of the cathodic solution has a great contribution to the cell voltage. When applying a 0.3 mm cathodic solution channel in the flow cell reactor, H₂O₂ is successfully synthesized at a cell voltage of 2.28 V with a current density of 300 mA cm⁻² and 97.1% faradaic efficiency. This corresponds to a 3.70 kW h kg⁻¹ H₂O₂ energy consumption, which is much lower than results in recent reports in the literature. The produced H₂O₂ can be directly used for synthesizing high-purity 2,2′-dibenzothiazole disulfide (MBTS) in nearly 100% yield, showing the potential industrial value of H₂O₂ electrosynthesis technology.