Ultrasensitive room-temperature detection of NO2 with tellurium nanotube based chemiresistive sensor

Te nanotubes were synthesized through a microwave reflux method that employed a mixture of polyethylene glycol and water as solvent. The water content was used to manipulate the boiling temperature of the solvent. Characterizations of the Te products with scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy and X-ray diffraction spectroscopy indicate that the growth of Te nanotubes is governed by both diffusion-limited depletion at the surface of seeds and dissolution–crystallization process. A chemiresistive sensor constructed with the as-prepared Te nanotubes exhibits excellent sensitivity and selectivity to trace amount of NO2 at room temperature, where the low detection limit is found to near 500 ppt. The response of the gas sensor is totally reversible with the assistance of UV irradiation, in which increasing the UV exposure reduces the sensor recovery time to less than 5 min. The great performance of this Te-based gas sensor is attributed to the large surface-to-volume ratio and high crystallinity of these Te nanotubes.