Two- and three-dimensional assemblies of carbon nanomaterials such as carbon nanotubes and graphene are necessary to harness their remarkable physicochemical properties in many clean energy, electronics, and biomedical applications. Herein we report a facile, economical, and versatile method for layer-by-layer fabrication of chemically-crosslinked carbon nanomaterial assemblies by ultrasonic spray coating combined with radical-initiated crosslinking reaction. The chemical, surface, and mechanical properties of the carbon nanomaterial coatings were characterized by Raman spectroscopy, atomic force microscopy, scanning- and transmission-electron microscopy, and nano-dynamic mechanical analysis. Our results indicate that the macroscopic 2D assemblies of crosslinked carbon nanotubes or graphene nanoparticles have surface uniformity, are chemically-crosslinked, and are mechanically robust. We further provide proof-of-concept demonstration of fabricating free-standing, porous, 3D single-walled carbon nanotube structures. Taken together, the results opens avenues toward adapting our method to enable 3D printing or additive manufacturing of all-carbon nanomaterial structures.

The development of energy storage device utilizing carbon nanomaterials possesses remarkably significant electrochemical performance. As compared to others, carbon nanomaterials including carbon black, graphene, activated carbon, and carbon nanotube have advantages in ion accessibility and specific surface area in which, more charged ions can access and transfer to the surfaces of material and thus have enhanced electrical charge storage performance. This manuscript briefly reviews the deposition of carbon nanomaterials from electrophoretic deposition technique which is good because of its simple, economical, versatility, and possibility of the thin film deposition on large substrate. The current state-of-the-art and performance of devices employing carbon as electrode material is also extensively discussed.

Dispersions containing 1 mg/mL of several carbon nanomaterials were used to deposit films containing 1 to 20 layers. The electrical properties of the composite films were characterized via impedance spectroscopy along two directions: in-plane on the film topmost surface and also through the thickness. It was found that carbon black nanoparticles never achieved full in-plane interconnection while the multiwalled carbon nanotube (MWNT) and single-walled carbon nanotube were already percolated at one layer. Graphite flakes showed a complete percolation curve that allowed its resistance to change by 6–7 orders of magnitude. The differences in the microstructure, electrical response, and thermal decomposition behavior of these carbon nanomaterial–paper substrate films were explained by detailed equivalent circuit analysis of the impedance spectra. Interpretation was supplemented by scanning electron microscopy images and thermal analysis via Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA). Thru-plane electrical properties were for the most part similar, although only films with short MWNT showed a clearly infiltrated network structure.