Effect of layer charge modification for Co-Al layered double hydroxides: study by X-ray absorption spectroscopy

摘要

When tuning the exchange capacity of a Co~(2+), A1~(3+) containing layered double hydroxyde's (LDH's) material, a concomitant phenomenon of oxidation-migration of the cations is observed for one of the end members. X-ray absorption spectroscopy, performed at the cobalt and aluminum k-edge, shows that part of the Co~(2+) cations are oxidized to Co~(3+), while A1~(3+) cations have left the LDH's layers, leading to a (Co_x~(2+)Co~(3+)) intralayer composition. Interlamellar AlO_6 polyhedra are present after repetitive washing and exchange reactions, suggesting strong interactions with the LDH's layers.