We present lightweight macro-mesoporous spinel CoAl2O4 nanostructured aerogels derived from water-soluble aluminum-chitosan complexes. Chitosan nanofibrils interact with aluminum ions to swell into hydrogels. The aluminum-induced swelling is extended to dissolve the hydrogels in water to form a homogeneous aluminum-chitosan aqueous solution. The addition of cobalt ions in the aluminum-chitosan liquids which are solidified by lyophilization to generate cotton-like aerogel composites. Uniform incorporation of cobalt-aluminum hydroxide ions onto chitosan leads nanofibrils to serve as a hierarchical template to support mixed metal hydroxides in the aerogel composites. We investigated the thermal removal of chitosan template in the composites to obtain spinel CoAl2O4 aerogels that truly replicate spider web-like fibrillar networks of chitosan template. Enlarged porosity, high crystallinity, and lightweight make the CoAl2O4 aerogels useful as a colorful nano-pigment for magnetic ceramics.
CHITOSAN-TEMPLATED LIGHTWEIGHT SPINEL CoAl2O4 NANOFIBRIL AEROGELS
