Three-Dimensional Nitrogen-Doped Multiwall Carbon Nanotube Sponges with Tunable Properties

Abstract

A three-dimensional (3D) nitrogen-doped multiwall carbon nanotube (N-MWCNT) sponge possessing junctions induced by both nitrogen and sulfur was synthesized by chemical vapor deposition (CVD). The formation of "elbow" junctions as well as "welded" junctions, which are attributed to the synergistic effect of the nitrogen dopant and the sulfur promoter, plays a critically important role in the formation of 3D nanotube sponges. To the best of our knowledge, this is the first report showing the synthesis of macroscale 3D N-MWCNT sponges. Most importantly, the diameter of N-MWCNT can be simply controlled by varying the concentration of sulfur, which in turn controls both the sponge's mechanical and its electrical properties. It was experimentally shown that, with increasing diameter of N-MWCNT, the elastic modulus of the sponge increased while the electrical conductivity decreased. The mechanical behaviors of the sponges have also been quantitatively analyzed by employing strain energy function modeling.

The synthesis of carbon nanomaterials using chlorinated hydrocarbons over a Fe-Co/CaCO3 catalyst

“…Modification of CNTs has thus led to the creation of new functional and construction materials. 11 Doping of the carbonaceous materials with non-carbon atoms, such as nitrogen, [12][13][14][15][16][17][18][19] boron, [20][21][22][23][24] sulphur, [25][26][27][28][29] oxygen [30][31][32][33][34][35][36] and halogens 11,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] has been explored over the past two decades. Modification of the carbon surface and electronic properties has also been explored but the effect of chlorine (Cl) on the morphology of carbon nanomaterials is not well established.…”

Three-Dimensional Porous Architectures of Carbon Nanotubes and Graphene Sheets for Energy Applications

“…Zhao et al (2011) sputtered Fe catalysts on the surface of Ni foam for the growth of 3D randomly entangled CNTs. Shan et al (2013) synthesized 3D sponge-like N-doped CNT architecture, employing the mixture of ferrocene, thiophene, and pyridine as CVD precursors. The N and S are proposed to synergistically promote the formation of "elbow" and "welded" junctions between CNTs.…”

Hyperelasticity of three-dimensional carbon nanotube sponge controlled by the stiffness of covalent junctions

“…However, it remains a great challenge to fabricate CNT sponges that reflect the mechanical properties of individual CNTs. Previous studies have shown compressive modulus values of these sponges fall in the range of kPa [6]. In human body, through the control of topology and organization, collagen fibers can form into various tissues with drastically different mechanical functions, such as cartilage, ligament, and skin, by controlling their topology [11].…”

“…We have used this technique successfully in generating a 3-D boron-doped multi-walled CNT (CBxMWCNT) sponge, in which the formation of atomic-scale ''elbow-like'' junctions in CNT reforms the nanotube into a 3-D multi-segment architecture [4]. Recently, we also synthesized 3-D nitrogen-doped CNT (N-MWCNT) sponges by introducing nitrogen into the CNT structures [6]. Although both 3-D CNT sponges demonstrate prominent hyperelastic properties with nonlinear stressestrain relationship, which makes them good candidates for load support with a shock absorption capability, they showed entirely different hyperelastic behaviors.…”