N-doped magnetic three-dimensional carbon microspheres@TiO2 with a porous architecture for enhanced degradation of tetracycline and methyl orange via adsorption/photocatalysis synergy

Organic contaminants in aquatic ecosystems have raised serious environmental concerns and pose severe risks to human health, and the catalytic efficiency of traditional TiO 2 catalysts has been greatly limited by photogenerated electron/hole recombination. Therefore, a novel catalyst of N-doped magnetic three-dimensional (3D) carbon microspheres@TiO 2 with a nanofibrous porous architecture (N-doped MCMs@TiO 2 ) was developed from the low-cost biomass of chitin. The N-doped MCMs@TiO 2 consist of N-doped carbon nanofibers, a 3D porous architecture, and a high surface area. TiO 2 nanoparticles were uniformly immobilized on the N-doped carbon nanofibers, resulting in many catalytic sites. The current density of N-doped MCMs@TiO 2 was approximately 0.247 uAcm −2 with 1.65 times than that of pure TiO 2 , and the bandgap of N-doped MCMs@TiO 2 was only 1.91 eV. Additionally, N-doped MCMs@TiO 2 had excellent adsorption capability for tetracycline (TC) (60.38%) and methyl orange (MO) (40.15%) in the dark after 40 min. Under the optimized conditions, N-doped MCMs@TiO 2 exhibited remarkable photodegradation performance for MO and TC mixture solutions, the degradation efficiencies of MO and TC were approximately 83.80% and 74.37% under UV irradiation, and that of was maintained at 68.07% and 76.55% even in cloudy weather, respectively. Meanwhile, N-doped MCMs@TiO 2 possess good potential for practical applications with long-term stability and can be easily recycled from solutions under an external magnet. Therefore, this work provides new insight into the fabrication of low-cost biomass-based 3D hierarchical porous carbon materials and that can be used as high-performance photocatalysts for the degradation of organic contaminants.