Arc-discharge-assembled CNT/MoO3 nanohybrids for ultra-sensitive and selective sub-ppm ethanol detection at room temperature

Abstract

In this study, one-dimensional carbon nanotube (CNT) and zero-dimensional MoO₃ nanohybrids were synthesized using a simple arc-discharge method for ethanol gas sensor applications. MoO₃ nanoparticles were uniformly distributed on the surface of mesoporous CNTs, which increased the specific surface area and the availability of active sites for charge carriers within the nanohybrid. MoO₃ functions as the receptor, while the CNTs serve as the transducer, leading to the modification in the depletion region at the hybrid surface, followed by enhancement of the sensing performance. The CNT/MoO₃ sensor exhibited the highest response of 76.5% to 1 ppm ethanol even at room temperature operation (30 °C), significantly outperforming CNT (12.5%) and MoO₃ (2.5%). Additionally, the CNT/MoO₃ sensor revealed rapid response and recovery time, excellent selectivity, and minimal humidity dependence. SEM, TEM, XRD, XPS, and BET analyses confirmed that the improved gas sensitivity of the CNT/MoO₃ nanohybrid is attributed to the increased active sites for charge carriers, abundant surface vacancies, and modification in the depletion region.