Penta nitrogen coordinated cobalt single atom catalysts with oxygenated carbon black for electrochemical H2O2 production

The two-electrons (2e–) oxygen reduction reaction (ORR) offers a sustainable and decentralized alternative to the traditional synthetics for hydrogen peroxide (H2O2) production. Although various Co single atom catalysts (SACs) have been proposed as highly effective 2e– ORR catalysts, there is still room for improvement through fine-tuned coordination environment. Here, a Co-N5-O-C with the combination of highly coordinated Co-N5 moieties and nearby electro-withdrawing epoxides is first time developed to reach the optimal binding energy of *OOH intermediate, resulting in the ultrahigh mass activity of 87.5 A g−1 at 0.75 V vs. RHE. Moreover, a high H2O2 production rate of 11.3 mol g−1 h−1 at 200 mA cm−2 is also obtained by a flow cell device. Such an efficient in-situ generation of H2O2 further enables 100% degradation of the organic methylene blue pollutant within 15 min through the electro-Fenton process. These findings will provide a new direction for on-site H2O2 synthesis and wastewater treatment. [Display omitted] •Penta nitrogen coordinated Co single-atom catalyst with rich-epoxy groups is synthesized.•DFT calculation reveals Co-N5 with epoxy oxygen has the most favorable binding energies of *OOH for 2e- ORR.•Up to 85.6% high selectivity and ultrahigh mass activity of 87.5 A g−1 for H2O2 production can be reached.•Outstanding H2O2 production rate of 11.3 mol g−1 h−1 is achieved under high current density using a flow cell.•Effective organic MB pollutant degradation is demonstrated using an electro-Fenton system.