Percarbonate activation by N-doped polyethylene terephthalate (PET)-derived carbon: The role of vacancy and insights into the mechanism

Percarbonate-based advanced oxidation processes catalyzed by carbon materials from plastic waste are rarely reported and lack clarity in their mechanisms. We synthesized N-doped polyethylene terephthalate (PET)-derived carbon materials with surface areas of up to 2190.9 m2/g and nitrogen/oxygen vacancies via urea-assisted pyrolysis. These materials exhibited exceptional adsorption and catalytic activities in a Fenton-like reaction for tetracycline degradation. The N-doped PET-derived catalyst (NPETK-800) achieved a 95 % removal efficiency for tetracycline at 50 mg/L, attributed to synergistic adsorption and oxidation effects via sodium percarbonate activation. NPETK-800 underwent surface hydroxylation through the electrostatic adsorption of OH− from CO32− hydrolysis on N and O vacancies, and its hydroxylated surface converted the adsorption mode of H2O2 to a H-bonded structure. This mode favored cleaving the OH bond over the OO bond in H2O2, generating 1O2 and O2−, crucial for tetracycline degradation. This study unveils the pivotal role of vacancies in tuning the generation of reactive oxygen species in Fenton-like reactions.