Structure and catalysis of layered rock-salt type oxides for methane oxidation

A comparison of X-ray photoemission spectra of LiFeO2, LiCoO2, and LixNi2−xO2 for the range of 0 < x ≤ 1 have been measured. A main O 1s XPS peak of LiNiO2 and LiCoO2 with a hexagonal type was observed at 531.9 eV, while that of LiInO2, LiFeO2 with a tetragonal type and LixNi2−xO2 (x < 0.6) with a cubic type were about 531.4 eV. It was inferred from these results that the layered superstructure of LiNiO2 and LiCoC2 largely affected the formation of the active oxygen species for the high selective coupling reaction of methane.