Metal–organic complex-derived 3D porous carbon-supported g-C3N4/TiO2 as photocatalysts for the efficient degradation of antibiotic

Abstract

Metal–organic complexes (MOCs) derived porous carbon have attracted considerable attention due to easy functionalization with metal/metal oxides or other heteroatoms and hierarchical porosity. Herein, four g-C₃N₄/TiO₂/CNOT photocatalyst structures were prepared via a reasonable design and control of the amount of MOC crystal materials. g-C₃N₄/TiO₂/CNOT photocatalysts have a 3D porous structure, high surface area and heterojunction interface between g-C₃N₄ and TiO₂, which together enhance the adsorption and photocatalytic performance. The 3D porous structure of g-C₃N₄/TiO₂/CNOT supplied multidimensional adsorption-enrichment sites, and the heterojunction promoted the separation of the photogenerated electrons and holes. The g-C₃N₄/TiO₂/CNOT-15 photocatalyst with the highest surface area reached up to 1644.1 m² g⁻¹. Heterojunctions promoted the separation and migration of the photogenerated electrons and holes. Benefiting from the above-mentioned excellent characteristics, g-C₃N₄/TiO₂/CNOT exhibits efficient synergistic adsorption–photocatalysis performance for the removal of chlortetracycline hydrochloride (CTC-HCl). Apparently, g-C₃N₄/TiO₂/CNOT-15 shows the highest CTC-HCl photocatalytic efficiency up to 97.8% after 60 min in the static system. In the dynamic system, the maximum CTC-HCl removal rate reached 35.5% and equilibrium removal rate was 19.9%. Free radical trapping experiments demonstrated that ˙O₂⁻ radical, ˙OH radical and holes serving as active species work together to promote photocatalytic reactions. This study provides a clear direction for the preparation of a 3D porous heterojunction for the efficient removal of antibiotics via synergy adsorption and photocatalysis.