Fabrication of TeNT/TeO₂ heterojunction based sensor for ultrasensitive detection of NO₂

Tellurium nanotubes (TeNT) heterojunction with Tellurium oxide (TeO₂) were prepared by in situ oxidation at elevated temperatures in air. The chemiresistive type NO₂ sensor was then fabricated by depositing the synthesized TeNT/TeO₂ on the integrated gold electrodes. The response of the TeNT/TeO₂ based sensor to 600 ppb NO₂ was 38.8 %, which was about 3.2 times higher than that of the single-phase TeNT based sensor (12.1 %). The response and recovery time are 39 s and 49 s, respectively, which are substantially reduced compared to those of the pristine TeNT based sensor (133 s and 336 s) and the results reported in literature. The sensor also exhibits good stability with a response deviation of less than 2 % for 45 days and a good resistance to environmental disturbances. The improved sensor performance can be attributed to the heterojunction formed between TeNT and TeO₂. Density Functional Theory (DFT) calculations show that the formed TeNT/TeO₂ heterojunction enhances the adsorption energy (-0.671 eV) and charge transfer (0.49 |e|) between NO₂ and the TeNT/TeO₂.