Electrochemical Synthesis of Hydrogen Peroxide Catalyzed by Carbon Nanotubes with Surface Co-N Sites and Encapsulated Co Nanoparticles.

The exploitation of M-N sites, where M is a transition metal atom, is widely regarded as an effective catalytic strategy to promote the oxygen reduction reaction (ORR). In addition, some studies have shown that transition metal nanoparticles (M-NPs) coated with carbon layers can improve the reactivity of ORR and ameliorate the overpotential of the reaction. In this study, we synthesized carbon nanotubes with single-atom Co-N active sites, Co-NPs outside the tube, and Co-NPs wrapped in the tube by the complexation-pyrolysis synthesis method and explored the role of the particles and Co-N sites through different pickling steps. The catalyst synthesized with the new stratagem in this study shows outstanding selectivity and also ORR activity. Furthermore, a natural air diffusion electrode fabricated using this material can produce HO at 323 mg L h under neutral conditions without oxygen aeration.