N/O co-doped porous carbon derived from polyester waste for electrochemical production of H2O2

Abstract

Electrochemical synthesis of hydrogen peroxide (H₂O₂) has been considered as an ideal alternative to traditional anthraquinone techniques due to its convenient operation and environmental friendliness. However, the development of catalysts with high activity, selectivity, and stability is still an important challenge. In this study, waste polyethylene terephthalate (PET) was converted into a high-value carbon-based catalyst for the electrochemical production of H₂O₂. Nitrogen–oxygen co-doped porous carbon (NOPC) was obtained by pyrolysis of PET with addition of melamine as a nitrogen source and magnesium oxide (MgO) as a templating agent. The cross-linking reaction during the pyrolysis process tightly bound nitrogen (N) and oxygen (O) active sites via amide group formation. These groups were uniformly distributed within the carbon matrix, accompanied by numerous defects, thereby enhancing both activity and selectivity. The optimized PET-derived NOPC catalysts exhibited a H₂O₂ selectivity of approximately 85% with an electron transfer number close to 2.3, and demonstrated long-term stability for over 10 hours in acidic solution. The electrocatalytic H₂O₂ yield in a custom-built cell reached 261.23 mmol g_catalyst⁻¹ h⁻¹ with faradaic efficiency above 80%. This work presents an efficient synthesis method for 2-electron oxygen reduction reaction (2e⁻ ORR) electrocatalysts and provides a sustainable strategy for recycling waste plastics into valuable carbon materials.