XPS of Nitrogen-Containing Functional Groups Formed during the C−NO Reaction

The reaction between nitrogen oxides and carbon generates nitrogen-containing complexes on the carbon surface. The use of X-ray photoelectron spectroscopy allowed the characterization of these surface complexes. Five distinct structures have been distinguished, corresponding to nitrogen incorporated in five- and six-member ring as well as pyridine N -oxide and nitrate. Temperature has been found to be the determinant in the repartition of surface species. The reaction with NO−O 2 at 600 °C has produced both pyrrolic and pyridinic nitrogens, while the reaction with NO at 950 °C mainly produced a pyridinic one. Quaternary nitrogen increased upon the heat treatment in He at 950 °C after the char was reacted with NO−O 2 at 600 °C.