Fig. 2: Characterizations of Co sites in the CoPc-OCNT catalyst.

a XRD patterns of CoPc-OCNT with different Co loadings. b FT-IR spectra of OCNT, CoPc-OCNT and CoPc reference. c Co 2p, N 1s and O 1s high-resolution XPS spectra of CoPc-OCNT and the reference materials (Co foil, Co3O4 and CoPc). d XANES and e–f FT-EXAFS curves at R space of Co K-edge and the corresponding fittings for CoPc-OCNT and the reference materials (Co foil and CoPc).