Cu0 incorporated cobalt/nitrogen doped carbonaceous frameworks derived from ZIF-67 (Cu@CoNC) as PMS activator for efficient degradation of naproxen: Direct electron transfer and 1O2 dominated nonradical mechanisms

In this study, zero valent copper (Cu 0 ) was incorporated into ZIF-67 to construct Cu 0 and cobalt/nitrogen doped carbonaceous frameworks x -Cu@Co N C y . The obtained Cu@Co N C was employed to activate PMS to degrade naproxen (NPX) in aqueous phase. Influencing factors on NPX degradation were investigated, including mole ratio of Cu/Co, pyrolysis temperature, pH, catalyst dosage, PMS concentration, and coexisting inorganic anions. In the presence of 0.5 mM PMS and 25 mg/L 1:3-Cu@Co N C 900, complete degradation of NPX (50 μM) could be achieved in 20 min within a wide pH range of 3 to 10. The superior catalytic activity of Cu@Co N C 900 for PMS activation was related to the increased surface –OH groups, accelerated electron transfer rate induced by Cu 0 with strong conductivity, formed surface PMS complexes with high oxidation activity, and synergistic effect between Cu and Co. EPR analysis, radical scavenging and probe tests excluded the participation of SO 4 − and OH in NPX degradation. Nonradical pathways of electron transfer from NPX to PMS and 1 O 2 oxidation contributed to the excellent degradation. The 1:3-Cu@Co N C 900 demonstrated a decent degradation performance even after five consecutive recycles with low cobalt and copper ions leaching due to the encapsulation of Co and Cu on N -doped porous carbon. Further, the intermediates of NPX degradation were identified, and three possible degradation pathways were proposed. Overall, this work provides a feasible strategy to improve the stability and catalytic activity of ZIF-67 by the incorporation of Cu 0 .