Highly efficient removal of tetracycline hydrochloride by CuNi-C MOF: Activation of oxygen via radical and non-radical pathways

• CuNi-C/Air system exhibited wide pH adaptation (3–10) for adsorption and oxidation. • O 2 from air was activated via radical and non-radical pathways on CuNi-C surface. • ⋅O 2 – was the dominant ROS generated from O 2 activated on Cu(0) surface. • CuNi-C-mediated electron transfer resulted in the non-radical activation of oxygen. • N, O-doped graphitic carbon provided active sites for mediated electron transfer. This work successfully synthesized an outstanding catalyst with high surface area and Cu(0) particles encapsulated in the hierarchically mesoporous structure (CuNi-C), via the pyrolysis of metal organic frameworks (MOFs). CuNi-C exhibited high efficiency for adsorption and great catalytic performance for the oxidative degradation of tetracycline hydrochloride (TC) by activating the dissolved oxygen (DO) with wide pH adaptation (3–10), as well as great recycled performance. It was confirmed by the effect of inorganic anions, quenching experiments, electron paramagnetic resonance (EPR) technology, and electrochemical tests (CV, LSV and OCP) that the outstanding oxidative effectiveness of the CuNi-C/Air system was the credit of the radical (·O 2 – ) and non-radical pathways (mediated electron transfer). Characterizations including HRTEM, HAADF-STEM, XPS and FTIR indicated that the Cu(0) particles encapsulated in the outer graphitic carbon, could transform DO to ·O 2 – and H 2 O 2 . It was also proposed that the N, O-doped graphitic carbon framework provided the main active sites (–OH group, graphitic N and pyridinic N) as the powerful platform for stabilizing oxygen and TC on the CuNi-C surface, which was a key step for non-radical process to initiate the electron transfer. Overall, this work provides a facile and efficient method for organic pollutants decomposition.