Porous hierarchical sphere g-C3N4 with coordinated Co-ions as an efficient and stable self-Fenton photocatalyst for the removal of antibiotic

Photocatalysis-self-Fenton reaction is a promising antibiotics-contaminated wastewater treatment method, but it is still limited by the leakage and sluggish cycling of metal-ions activating sites. Herein, a novel porous hierarchical sphere g-C3N4 with coordinated Co-ions (HCN-Co) was successfully synthesized by a supramolecular modified calcination strategy. The hierarchical sphere structure and coordinated Co-ions of HCN-Co exhibited a synergistic effect on enhancing visible-light absorption, stabilization of Co-ions, charge transfer and surface reaction, which leaded to increased H2O2 generation and activation under visible-light irradiation. Consequently, HCN-Co displayed remarkable and stable photocatalysis-self-Fenton degradation of ciprofloxacin (CIP) with an optimal removal percentage of 99.9 % under visible-light irradiation for 50 min. In this photocatalysis-self-Fenton reaction, H2O2 was generated from 2-step single-e− oxygen reduction reaction and activated to hydroxyl radical (OH) by Co2+ refreshing from interface charge transfer (IFCT) excitation. This work presents a viable approach and provides valuable insights for developing efficient photocatalysis-self-Fenton system for wastewater remediation.