Structure and transport properties of amorphous carbon-based foams derived from coal

Carbon foams, often manufactured from coal, have shown promise as sustainable building materials with engineerable thermoelectric properties, and they offer a unique playground for studying the physics of disordered systems at different scales. Here, we apply experimental techniques to probe the chemical makeup, bulk thermoelectric properties, and structural scaling behaviors of several commercially produced carbon-based foams. The foams vary from highly amorphous to almost entirely graphitic, dominated by carbon but containing various impurities. The quality and fractal scaling of their micro- and meso-porous structures are investigated by direct imaging and X-ray scattering. The samples demonstrate good thermal insulation in both porous and powder forms, while their electrical conductivities, probed by Hall effect measurements, are significantly correlated with the sample type.