The bulk synthesis of freestanding carbon nanotube (CNT) frameworks is developed through a sulfur-addition strategy during an ambient-pressure chemical vapour deposition process, with ferrocene used as the catalyst precursor. This approach enhances the CNTs' length and contorted morphology, which are the key features leading to the formation of the synthesized porous networks. We demonstrate that such a three-dimensional structure selectively uptakes from water a mass of toxic organic solvent (i.e. o-dichlorobenzene) about 3.5 times higher than that absorbed by individual CNTs. In addition, owing to the presence of highly defective nanostructures constituting them, our samples exhibit an oil-absorption capacity higher than that reported in the literature for similar CNT sponges.

The dependence of electrical conductivity on compression of a freestanding three-dimensional carbon nanotube (CNT) network is investigated. This macrostructure is made of mm-long and entangled CNTs, forming a random skeleton with open pores. The conductivity linearly increases with the applied compression. This behaviour is due to increase of percolating pathways-contacts among neighbouring CNTs-under loads that is highlighted by in situ scanning electron microscopy analysis. The network sustains compressions up to 75% and elastically recovers its morphology and conductivity during the release period. The repeatability coupled with the high mechanical properties makes the CNT network interesting for pressure-sensing applications.