Carbonate-induced electrosynthesis of hydrogen peroxide via two-electron water oxidation

Abstract

Electrochemical synthesis of hydrogen peroxide (H2O2), via the two-electron water oxidation reaction (2e– WOR), is an attractive method for the sustainable production of valuable chemicals in place of oxygen during water electrolysis. While the majority of 2e– WOR studies have focussed on electrocatalyst design, little research has been carried out on the selection of the supporting electrolyte. In this work, we investigate the impact of potassium carbonate (K2CO3) electrolytes, and their key properties, on H2O2 production. We find that at electrolyte pH values (> 9.5) where the carbonate anion (CO32–) is prevalent in the mixture, a 26.5% increase in the Faraday efficiency (%FE) for H2O2 production is achieved, compared to bicarbonate (HCO3–) dominant solutions. Utilising boron-doped diamond (BDD) in highly concentrated K2CO3 solutions, current densities of up to 511 mA cm-2 (in 4 M) and %FEs of 91.5% (in 5 M) can be attained. The results presented in this work highlight the influence of CO32– on electrochemical H2O2 generation via the 2e– WOR and provide novel pathways to produce desirable commodities at the anode during electrochemical water splitting.

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Identifiers

ORCID for Ling Wang: orcid.org/0000-0002-2894-6784

ORCID for Carlos Ponce De Leon Albarran: orcid.org/0000-0002-1907-5913

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