Concurrent oxygen reduction and water oxidation at high ionic strength for scalable electrosynthesis of hydrogen peroxide

Changmin Kim; Sung O Park; Sang Kyu Kwak; Zhenhai Xia; Guntae Kim; Liming Dai

doi:10.1038/s41467-023-41397-1

Concurrent oxygen reduction and water oxidation at high ionic strength for scalable electrosynthesis of hydrogen peroxide

Nat Commun. 2023 Sep 19;14(1):5822. doi: 10.1038/s41467-023-41397-1.

Authors

Changmin Kim¹, Sung O Park², Sang Kyu Kwak^{2

3}, Zhenhai Xia¹, Guntae Kim⁴, Liming Dai⁵

Affiliations

¹ Australian Carbon Materials Centre (A-CMC), School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.
² Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
³ Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, South Korea.
⁴ Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800, China. gtkim@sinap.ac.cn.
⁵ Australian Carbon Materials Centre (A-CMC), School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia. l.dai@unsw.edu.au.

Abstract

Electrosynthesis of hydrogen peroxide via selective two-electron transfer oxygen reduction or water oxidation reactions offers a cleaner, cost-effective alternative to anthraquinone processes. However, it remains a challenge to achieve high Faradaic efficiencies at elevated current densities. Herein, we report that oxygen-deficient Pr_1.0Sr_1.0Fe_0.75Zn_0.25O_4-δ perovskite oxides rich of oxygen vacancies can favorably bind the reaction intermediates to facilitate selective and efficient two-electron transfer pathways. These oxides exhibited superior Faradic efficiencies (~99%) for oxygen reduction over a wide potential range (0.05 to 0.45 V versus reversible hydrogen electrode) and current densities surpassing 50 mA cm^-2 under high ionic strengths. We further found that the oxides perform a high selectivity (~80%) for two-electron transfer water oxidation reaction at a low overpotential (0.39 V). Lastly, we devised a membrane-free electrolyser employing bifunctional electrocatalysts, achieving a record-high Faradaic efficiency of 163.0% at 2.10 V and 50 mA cm^-2. This marks the first report of the concurrent oxygen reduction and water oxidation catalysed by efficient bifunctional oxides in a novel membrane-free electrolyser for scalable hydrogen peroxide electrosynthesis.