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

## TL;DR

A new sensor made of carbon nanotubes and molybdenum oxide detects ethanol at very low levels even at room temperature.

## Contribution

This is the first study to use CNT/MoO3 nanohybrids for ultra-sensitive ethanol detection at room temperature.

## Key findings

- The CNT/MoO3 sensor showed a 76.5% response to 1 ppm ethanol at 30°C.
- The sensor has rapid response and recovery times, excellent selectivity, and minimal humidity dependence.
- The sensing mechanism does not rely on the traditional chemisorbed oxygen theory.

## 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.

(1) This is the first study of CNT/MoO3 for ethanol sensing detection at room temperature with rapid response and recovery times. (2) The commonly accepted chemisorbed oxygen theory no longer plays a dominant role in the sensing mechanism.