The morphology of cyanide-bridged palladium-cobalt (Pd-Co) gels, synthesized from aqueous solutions of Na2PdCl4 and K 3[Co(CN)6], is elucidated using nitrogen and carbon dioxide adsorption, permeability measurements, electron microscopy, and small-angle X-ray scattering. The aerogels formed from the Pd-Co hydrogels possess both micro- and mesoporosity. Electron microscopy indicates that the aerogels are constituted of spherical microporous particles; the interstices between these particles constitute the mesopores. The aerogel surfaces are found to be fractal as analyzed by gas adsorption and small-angle X-ray scattering. Both these techniques yield, within experimental error, the same surface fractal dimension of 2.6 ± 0.2 for the aerogels. The Pd-Co xerogels, unlike the aerogels, are predominantly microporous with a narrow microporosity. Transmission electron microscopy reveals that the xerogels are constituted of particles of an average size of ∼10 nm. Unlike the aerogels, the xerogels do not possess surface fractality. The mechanism of adsorption of different gases on these gels is analyzed on the basis of the gel morphologies.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry