Carbon nanotubes (CNTs) are a one-dimensional (1-D) allotrope of carbon, made up of a sp 2 hybridized carbon lattice in the form of a cylinder. A single-wall CNT (SWCNT), the simplest version of a CNT, consists of a single, cylindrical graphene tube. In double-wall CNTs (DWCNTs) and multi-wall CNTs (MWCNTs), two or more tubes are either nested concentrically or wrapped like a scroll. SWCNTs are typically 0.4-2 nm in diameter, while MWCNTs can be much larger, with diameters of tens of nanometers, having both ends generally capped by fullerene-like domes. Similar to fullerenes and graphene, which are the analogous 0-and 2-D allotropes of carbon, the graphite-like arrangement of carbon atoms in CNTs and their shape give them remarkable and unique properties, which has resulted in the widespread use of CNTs in several fields of science and technology, including energy storage, electronics, structural composites, biomaterials, and others. These properties include a high Young's modulus (0.27-1.8 TPa) and tensile strength (11-63 GPa). CNTs are stable in vacuum up to 1225-1400 °C, though their stability is compromised in oxidizing environments (in air they decompose through oxidation at 400-550 °C). Because of their 1-D structure, CNTs have highly anisotropic mechanical, electrical, and thermal properties, which make them ideal for use in polymer, ceramic, and metal matrix composites. Additionally, their electrical properties, very high surface to volume ratio, and potential for chemical functionalization has led to their use in battery and supercapacitor components. The electrical properties of CNTs are primarily determined by the configuration of the C-C bonds relative to their macroscale orientation. CNTs can have three configurations: armchair, zigzag, and chiral. Armchair-configured CNTs, which are achiral, are electrically similar to metals, while the zigzag (also achiral) and chiral CNTs are semiconducting. In the following sections, we will discuss the trends in CNT-related research from 2003 to 2023, with a focus on identifying the emerging topics of research in this area over the last 3 years. This analysis was performed by first identifying journal and patent publications in the CAS Content Collection™ related to CNTs, which resulted in a set of roughly 270,000 documents. We identified emerging applications, materials, applications, properties, and other concepts in CNT-related research using a Natural Language Processing (NLP) based approach. This analysis identified over 39,000 concepts that appear in at least 20 documents, which were then classified, counted, grouped, and analyzed. The content of the following sections is based on the results of this analysis, in combination with substances, concepts, and other information indexed in the CAS Content Collection. For a more detailed description of this process, please see the Methods section in the Supplementary Information.