Exsolved Co3O4 with tunable oxygen vacancies for electrocatalytic H2O2 production

The electrochemical production of hydrogen peroxide via the two-electron (2e(-)) oxygen reduction reaction (ORR) is an environmentally friendly method and is expected to be an alternative means to the industrial anthraquinone process. It is particularly suitable for on-site and small-scale H2O2 requirements. The development of earth-abundant catalysts with high activity and selectivity toward H2O2 is highly desirable and challenging. Here, we have prepared Co3O4 with tunable oxygen vacancies (OVs) and strongly coupled it to nitrogen-doped carbon nanotubes through an exsolution strategy. The Co3O4 with a higher OV concentration exhibits a higher 2e(-) ORR activity, higher H2O2 selectivity, and lower H2O2 reduction reaction (H2O2RR) activity so that effectively improving the production rate of H2O2 (1.6 mol peroxide/gcatalyst/h at 0.0 VRHE) in acidic media. The catalyst is also used as a cathode for the electro-Fenton process and degrades up to 80% of 40 mg/L of rhodamine B solution within 25 min. Density functional theory calculation shows that the *OOH binding energy (Delta G(*OOH)) could decrease on increasing the numbers of OVs, which subsequently benefits the protonation of *OOH to generate H2O2. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The electrochemical production of hydrogen peroxide through the two-electron oxygen reduction reaction offers an environmentally friendly alternative to the industrial anthraquinone process. Developing catalysts with high activity and selectivity for H2O2 production is essential for efficient and sustainable synthesis.