Fig. 4: DFT calculations for elucidating the underlying mechanisms.

a The adsorption energy of PMS on pristine graphene, pyridinic N, pyrrolic N and graphitic N. b Schematic diagram of I-NC configuration. c Charge density distribution images of N-doped carbon models with different configurations of graphitic N, I-NC. d The adsorption energy of PMS on N sites and C sites of graphitic N, graphitic N-D, and I-NC models. e Proposed reaction process for PMS oxidation to 1O2 on I-NC catalysts. f Potential energy profiles of the reaction pathway for generating the 1O2 species. Graphitic N-D model represent graphitic N with defect. Grey, blue, purple, red, yellow, and white spheres represent C, N, I, O, S, and H atoms, respectively. g Diagrammatic representation of the CIP degradation mechanism in the I-NC/PMS system. The purple region and dashed area in Fig. 4g denote I-NC’s active site and I-NC-PMS complex, respectively. Source data are provided as a Source Data file.