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

Abstract

Organic contaminants in aquatic ecosystems have raised serious environmental concerns and pose severe risks to human health, and the catalytic efficiency of traditional TiO2 catalysts has been greatly limited by photogenerated electron/hole recombination. Therefore, a novel catalyst of N-doped magnetic three-dimensional (3D) carbon microspheres@TiO2 with a nanofibrous porous architecture (N-doped MCMs@TiO2) was developed from the low-cost biomass of chitin. The N-doped MCMs@TiO2 consist of N-doped carbon nanofibers, a 3D porous architecture, and a high surface area. TiO2 nanoparticles were uniformly immobilized on the N-doped carbon nanofibers, resulting in many catalytic sites. The current density of N-doped MCMs@TiO2 was approximately 0.247 uAcm−2 with 1.65 times than that of pure TiO2, and the bandgap of N-doped MCMs@TiO2 was only 1.91 eV. Additionally, N-doped MCMs@TiO2 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@TiO2 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@TiO2 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.