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.