Diffuse-reflection spectroscopy applied to the structure of an aluminum-cobalt oxide system

NiAl and CoAl materials derived from takovite-like LDHs and related structures as efficient chemoselective hydrogenation catalysts

“…[34][35][36][37] The incorporation of cobalt in CoAl sample resulted in the formation of a three component absorption band positioned at ~450, 490 and 520 nm which was ascribed to Co 2+ in octahedral coordination. 38 Additionally, an absorption band centered at ~600 nm is observed and it may be attributed to d-d transitions in low spin of octahedrally coordinated Co 3+ cations. 39 Nevertheless, this band is much less intense in comparison to the band at ~520 nm, indicating that a minor amount of cobalt exists as Co 3+ .…”