Hierarchical microstructure and formative mechanism of low-density molybdena-based aerogel derived from MoCl5

Abstract

Low density 150 kg/m3 molybdena-based aerogel was prepared by using MoCl5 as precursor, polyacrylic acid (PAA) as additive and propylene oxide as gelation accelerator via the dispersed inorganic sol–gel method, followed by carbon dioxide supercritical fluid drying. Characterizations of the composition indicate that the as-synthesized aerogel is composed of molybdenum oxide and PAA derivatives; electron microscopy photographs show the hierarchical microstructure of the aerogel, including both spherical secondary particles and root-like primary fibers. Based on the analysis of coordination state and special morphology, it is suggested that the additive PAA not only guides the growth of the primary fibers but improves the crosslinkage between the secondary particles to form a robust skeleton.