Acid enhanced zipping effect to densify MWCNT packing for multifunctional MWCNT films with ultra-high electrical conductivity

Abstract

The outstanding electrical and mechanical properties remain elusive on macroscopic carbon nanotube (CNT) films because of the difficult material process, which limits their wide practical applications. Herein, we report high-performance multifunctional MWCNT films that possess the specific electrical conductivity of metals as well as high strength. These MWCNT films were synthesized by a floating chemical vapor deposition method, purified at high temperature and treated with concentrated HCl, and then densified due to the developed chlorosulfonic acid-enhanced zipping effect. These large scalable films exhibit high electromagnetic interference shielding efficiency, high thermoelectric power factor, and high ampacity because of the densely packed crystalline structure of MWCNTs, which are promising for practical applications.

All‐Automated Fabrication of Freestanding and Scalable Photo‐Thermoelectric Devices with High Performance

“…Second, the n‐type SWCNT films were densified to improve their thermoelectric power factors (PFs) by increasing the electrical conductivity ( σ ) and maintaining the Seebeck coefficient ( S ). [ 15 ] It is one of the key factors for high‐performance PTE devices. At last, the n‐type SWCNT films were cut into designed structures and created narrow‐transition area p–n patterns on them to make PTE devices by the laser automatically.…”

“…A similar dry‐compressing method has been proven to be an effective method to improve the thermoelectric performance of carbon nanotube films. [ 15b,c,17 ] Different from the dry compressing in previous works, the filtrated NDINE‐doped SWCNT films, SWCNT/NDINE 10:10 hybrid films, were compressed in wet at a pressure of 5 MPa, which were then dried in vacuum at 60 °C for 3 h, as illustrated in Figure 2c. The electrical conductivities for these densified SWCNT/NDINE 10:10 films increase dramatically by ≈2.8 times and reach a platform after being compressed for 18 min (Figure 2d).…”

“…The dramatic improvement of electrical conductivity is mainly attributed to the reduction of voids after compressing. [ 15b,c ] According to Maxwell–Eucken's equation, the electrical conductivity is inversely proportional to the porosity of a material. [ 15b,18 ] Scanning electron microscopy (SEM) was performed to qualitatively show the reduction of porosity, as shown in Figure S4 (Supporting Information).…”

Densification Induced Decoupling of Electrical and Thermal Properties in Free‐Standing MWCNT Films for Ultrahigh p‐ and n‐Type Power Factors and Enhanced ZT

“…The average diameter, length, and the average number of layers of walls were 2.85 nm, 20 μm, and 2.3 walls estimated from TEM images, respectively, as reported in our previous work. [32] The -highresolution TEM images (Figure S2, , Supporting Information) exhibited inter-layer spacing of nanotubes was 0.348 nm, which indicated high crystallinity and graphitic structure. [33][34][35][36] The morphology of the compressed individual MWCNTs remained similar to that of the pristine individual MWCNTs, and no large curvature buckled MWCNTs has been observed, as shown in Figures S3 and S2b (Supporting Information).…”

Enhancing the Interaction of Carbon Nanotubes by Metal–Organic Decomposition with Improved Mechanical Strength and Ultra-Broadband EMI Shielding Performance

“…Notably, carbon nanotubes (CNTs) stand out for their outstanding electrical conductivity, high mechanical strength, and ability for mass production, demonstrating enormous potential in the development of EMI shielding materials. The electrical conductivity of a single CNT is as high as 1 × 10 8 S m −1 , and the mechanical strength exceeds 100 GPa, owing to its strong C=C bond and large π-conjugated system [ 12 ]. Unfortunately, these excellent characteristics are still elusive in their macroscopic assemblies, such as CNT films.…”