Aerosol-Synthesized Surfactant-Free Single-Walled Carbon Nanotube-Based NO₂ Sensors: Unprecedentedly High Sensitivity and Fast Recovery

This study pioneers a chemical sensor based on surfactant-free aerosol-synthesized single-walled carbon nanotube (SWCNT) films for detecting nitrogen dioxide (NO2). Unlike conventional CNTs, the SWCNTs used in this study exhibit one of the highest surface-to-volume ratios. They showed minimal bundling without the need for surfactants and had the lowest number of defects among reported CNTs. Furthermore, the dry-transferrable and facile one-step lamination resulted in promising industrial viability. When applied to devices, the sensor has excellent sensitivity (41.6% at 500 ppb), rapid response/recovery time (14.2/120.8 s), a remarkably low limit of detection (below approximate to 0.161 ppb), minimal noise, repeatability for more than 50 cycles without fluctuation, and long-term stability for longer than 6 months. This is the best performance reported for a pure CNT-based sensor. In addition, the aerosol SWCNTs demonstrated consistent gas-sensing performance even after 5000 bending cycles, indicating their suitability for wearable applications. Based on experimental and theoretical analyses, the proposed aerosol CNTs are expected to overcome the limitations associated with conventional CNT-based sensors, thereby offering a promising avenue for various sensor applications. This article is protected by copyright. All rights reserved.