XAFS and XPS studies on the enhancement of methane adsorption by NiO dispersed ACF with the relevance to structural change of NiO

A remarkable enhancement of methane adsorptivity of activated carbon fiber (ACF) with dispersion of ultra fine NiO particles was observed. The Ni K-edge X-ray adsorption near-edge structures (XANES) and extended X-ray adsorption fine structures (EXAFS) spectra of dispersed NiO on ACF elucidated that the dispersed NiO showing the most remarkable enhancement effect has a specific structure whose nearest-neighbor atomic distance of NiO is larger than that of powdered NiO. The X-ray photoelectron spectroscopy (XPS) spectra suggested that the electrons of the ligand valence band in the dispersed NiO are tightly bound than those of the powdered NiO. (C) 2002 Elsevier Science B.V. All rights reserved.