Colors of Single‐Wall Carbon Nanotubes

Abstract

that when single-wall CNTs (SWCNTs) are sorted by diameter [7-10] or atomic structure [i.e., (n,m)], [11-14] they strikingly exhibit various distinct colors in suspension. More recently, colorful SWCNT thin films were produced by a novel one-step fabrication procedure, [15] enabling the direct synthesis of colorful SWCNTs that were previously thought impossible. Despite numerous studies on SWCNT colors, the coloration mechanism has not been fully understood. Currently, no theoretical model can reliably predict the color of a given SWCNT film. Namely, predicting the range of possible SWCNT colors has not been possible, nor has explaining why SWCNTs with certain atomic structures [specified by (n,m)] display stronger colors than other CNT species. This lack of understanding largely prevents us from further elaborating the controlled synthesis of color-specified SWCNT materials. Here, we report the results of both experimental and theoretical studies providing answers to these long-standing questions. First, by studying colored thin films with varying thicknesses, we established a quantitative relationship between the obtained colors and the optical absorption spectra of the films. This relationship confirms the absorption-dominated coloration mechanism of SWCNT-based films. Based on this finding, in combination with SWCNT optical absorption studies, we constructed a comprehensive theoretical model that can describe Although single-wall carbon nanotubes (SWCNTs) exhibit various colors in suspension, directly synthesized SWCNT films usually appear black. Recently, a unique one-step method for directly fabricating green and brown films has been developed. Such remarkable progress, however, has brought up several new questions. The coloration mechanism, potentially achievable colors, and color controllability of SWCNTs are unknown. Here, a quantitative model is reported that can predict the specific colors of SWCNT films and unambiguously identify the coloration mechanism. Using this model, colors of 466 different SWCNT species are calculated, which reveals a broad spectrum of potentially achievable colors of SWCNTs. The calculated colors are in excellent agreement with existing experimental data. Furthermore, the theory predicts the existence of many brilliantly colored SWCNT films, which are experimentally expected. This study shows that SWCNTs as a form of pure carbon, can display a full spectrum of vivid colors, which is expected to complement the general understanding of carbon materials.

Platinum-Nanoparticle-Modified Single-Walled Carbon Nanotube-Laden Paper Electrodes for Electrocatalytic Oxidation of Methanol

“…These films appeared gray rather than black, as is typically observed with conventional micron-scale SWCNT films. 31 To make paper-based electrodes, we cut the dried SWCNT paper into 24 individual strips (3 × 4 mm), attached these to copper wire with silver paste, and wrapped the assembly with Parafilm (Figure S4). We then deposited platinum nanomaterials onto the SWCNT paper electrodes through either electrochemical reduction of chloroplatinic acid (Figure 1E) or vacuum filtration of a solution of citrate-capped PtNPs (Figure 1F).…”

“…The thickness of the SWCNT films with a surface density of 8.3 μg/cm 2 was 160 ± 2 nm (Figure S2B), which demonstrated that a nanoscale-thickness film had formed on the paper surface. These films appeared gray rather than black, as is typically observed with conventional micron-scale SWCNT films . To make paper-based electrodes, we cut the dried SWCNT paper into 24 individual strips (3 × 4 mm), attached these to copper wire with silver paste, and wrapped the assembly with Parafilm (Figure S4).…”

Emerging Internet of Things driven carbon nanotubes-based devices

“…The random SWCNT network is ideal for fabricating transparent conductive films [94][95][96][97] because of their small diameter, good optical and electrical properties, and excellent flexibility. Recently, the floating metal catalyst CVD method is developed to achieve high quality, density, and purity SWCNTs deposited on substrate [98][99][100][101][102][103]. The high intertube Schottky junction resistance [103], existence of aggregated bundles of SWCNTs, and performance-yield tradeoff [102] are key issues, which may lead to a degraded electronic and optoelectronic performance of the films.…”

Superdurable and fire-retardant structural coloration of carbon nanotubes

“…Ever since the discovery of CNTs, it has always been a great challenge to render them with various colors. Although single-walled CNTs (SWCNTs) with narrow chirality distribution obtained by separation from mixtures can exhibit some colors, which strongly depend on the chiral structures of SWCNTs (9)(10)(11)(12), this method has serious restrictions and shortcomings. On the one hand, the chirality separation of SWCNTs with narrow distribution is a challenging, sophisticated, and timeconsuming technique that is only suitable for short CNTs (CNT powders) and usually exhibits colors in suspensions, but cannot be used for long CNTs and CNT assemblies such as fibers and films.…”