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 H 2 O 2 requirements. The development of earth-abundant catalysts with high activity and selectivity toward H 2 O 2 is highly desirable and challenging. Here, we have prepared Co 3 O 4 with tunable oxygen vacancies (OVs) and strongly coupled it to nitrogen-doped carbon nanotubes through an exsolution strategy. The Co 3 O 4 with a higher OV concentration exhibits a higher 2e − ORR activity, higher H 2 O 2 selectivity, and lower H 2 O 2 reduction reaction (H 2 O 2 RR) activity so that effectively improving the production rate of H 2 O 2 (1.6 mol peroxide/g catalyst /h at 0.0 V RHE ) 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 (Δ G ∗OOH ) could decrease on increasing the numbers of OVs, which subsequently benefits the protonation of ∗ OOH to generate H 2 O 2 .