N-doped carbon supported cobalt electrospun nanofibers activated peroxymonosulfate system for benzothiazole degradation: Multifunctional role of nitrogen species

• Catalytic materials with different N/C ratios were successfully prepared; • The unique role of different nitrogen species in Co@N/C-1:1 was revealed; • Co-N x formed after the introduction of Co is the main catalytic active sites; • The synergistic effect between Co/N improves the stoichiometric efficiency of PMS. Nitrogen doping is an effective way to enhance the activation performance in peroxymonosulfate (PMS) heterogeneous catalysis. However, the unique role of different nitrogen species was still controversial. Herein, N-doped carbon supported cobalt catalyst was synthesized by electrostatic spinning method and employed to activated PMS. Firstly, various nitrogen species in catalyst including graphitic N, pyridinic N, pyrrolic N and Co-N x was identified. Subsequently, the specific role of various nitrogen species was revealed by a series of experiments (adsorption experiments, degradation experiments, quenching tests, characterization analysis.), that is: 1) graphitic N changes the electrical of surrounding C atoms for PMS adsorption; 2) pyrrolic N with special pentacyclic structure leaded to obvious defects in carbon structure, thus enhancing the PMS activation ability of carbon materials; 3) pyridinic N bind with metal Co to form Co-N x , which acted as an efficient active site for PMS activation. In addition, the effects of pH, temperature, and coexisting ions were also studied. This study revealed the activation behavior of different N species on N-doped carbon supported transition metal base catalysts, which provides theoretical basis for further synthesis of N-containing catalysts with high activation efficiency and release the activation potential of N species.