Atomic and electronic structure of nitrogen-doped nano-graphene clusters by combined XPS and XAFS analysis

Changes in the local structure of nitrogen-containing carbon samples obtained by solid-phase pyrolysis of phthalonitrile and phthalocyanine at different pressures have been determined. The structure of carbon microspheres in the samples was studied by transmission electron microscopy. By combined analyzing the N $1s$ X-ray photoelectronic spectroscopy data (N $1s$ XPS) and fitting it with experimental N $K$-edge X-ray absorption near edge structure data (N $K$-edge XANES) the bond types and atomic structure parameters for the local structure of nitrogen in the synthesised samples have been determined. Bond lengths and angles in nitrogen-containing atomic configurations were determined, including three-atom C–N–C chains for pyridinic and pyrrolic nitrogen, as well as O=N–2C configurations for Quaternary nitrogen (QN) =Quaternary N (QN)=Oxidized N (ON). The percentage of these structural states of nitrogen in the samples and its dependence on the synthesis conditions were determined.