“…As shown in Figure a, the peaks of the N 1s spectra of MCCS-400, MCCS-400-Co, and ZIF-67@MCCS-400 were superimposed, and the peak of MCCS-400-Co shifted to the low-energy band region, indicating that there is an interaction force between Co and N. Moreover, when Co 2+ ions were used as metal sources to generate ZIF-67, the shift disappeared, indicating that this force disappeared. On the other hand, we further analyzed the Co 2p spectra of MCCS-400-Co, ZIF-67@MCCS-400, and ZIF-67 (Figure b); the Co 2p peaks at 781.1 and 782.7 eV in ZIF-67 represent Co-N x ( x < 4) and Co-N 4 coordination environments, − respectively, and the other two peaks were considered as satellite peaks. Compared to ZIF-67, the peaks for ZIF-67@MCCS-400 and MCCS-400-Co shifted to a lower binding energy, corresponding to Co-N x , suggesting a strong chemical bond forming between Co and pyridinic and/or pyrrolic-N with a high electronegativity, leading to partial electron migration from Co to pyridinic and/or pyrrolic-N.…”