Fig. 1.

Characterizations of Mn/N-HCN. A Schematic illustration for the synthesis of Mn/N-HCN. B TEM image. C Energy dispersive X-ray spectroscopy elemental mapping. D High-magnification HAADF-STEM image where the bright dots corresponding to individual Mn atoms are highlighted by red circles. E XRD patterns of N-HCN and Mn/N-HCN. F-G High-resolution N 1 s and Mn 2p XPS spectra of Mn/N-HCN. H-I XANES and EXAFS spectra at the Mn K-edge. J EXAFS fitting curve in R space