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.