Characterization of peroxide on coal surface: A combined △SCF and XPS study

X-ray photoelectron spectroscopy (XPS) is widely used to determine the composition of elements and oxygen-containing functional groups. Accurate determination of core-electron binding energies (CEBEs) is essential for identifying the types and contents of oxygen-functional groups present on the surface of coal. The △SCF method has been carried out on CEBEs for an extensive series of oxygen-containing organic systems encompassing the most common functionalities. The polymers for which experimental values are available for comparison demonstrate the adequacy of the treatment for describing CEBEs for the O1s core level. Therefore, a sound basis is provided for the discussion of CEBEs (O1s) for functionalities for which experimental values are not accurate or available, such as carbonyl, carboxyl, and peroxide. The results are applied to the XPS study of oxidized coal. The change law of peroxide and oxygen-containing functional groups was discussed. The calculation method and results in this paper can provide a guide for readers to use XPS to study the oxidation of coal surfaces.