Local, nano- and micro-structures of mixed metal oxide aerogels for catalyst applications

Sol-gel synthesis and processing have the potential to create catalytic sites atomically isolated in the aerogel framework. V or Cu were incorporated during the solution chemistry into silica aerogels. Extended X-ray absorption fine structure and X-ray absorption near edge structure were employed to determine that copper is present as an oxide and probably isolated in the silica matrix, while vanadium is present as V 2 O 4 and V 2 O 5 . High resolution transmission electron microscopy and selected area diffraction were used to elucidate the characteristics of the aerogel structure itself, including the diameter of the chains, as well as to look for phase separation and crystallinity of the active metal oxide. It was found that the metals were highly dispersed in the silica aerogel, even after oxidation and reaction treatments.