Abstract
The calcination of citrate-chelated cations is a time-honoured method to prepare dispersed oxides. The calcination of polysaccharide gels is also an effective method to prepare dispersed oxides. The ionotropic gelling of alginate, a natural block polysaccharide with carboxylic functions, implies the complexation of transition metal cations in an organic matrix whose texture can be easily controlled. Alginate hydrogel microspheres with 98 % porosity and more than 10 % cation content (w/w) can be formed. Supercritical drying preserves the dispersion of the gels and the resulting aerogels have specific surface as high as 500 m2 g-1. In this communication, the thermal degradation of alginate aerogels has been used to form oxide nanocrystals organized in open aggregates.