A High-Sensitivity Gas Sensor Toward Methanol Using ZnO Microrods: Effect of Operating Temperature

In the present work, zinc oxide (ZnO) microrods with the average diameter of 350 nm have been synthesized on fluorine doped tin oxide (FTO) substrate using a hydrothermal reaction process at a low temperature of 90A degrees C. The methanol gas sensing behaviour of as-synthesized ZnO microrods have been studied at different operating temperatures (100-300A degrees C). The gas sensing results show that the ZnO microrods exhibit excellent sensitivity, selectivity, and stability toward methanol gas at 300A degrees C. The as-grown ZnO microrods sensor also shows the good sensitivity for methanol even at a low operating temperature of 100A degrees C. The ultra-high sensitivity of 4.41 x 10(4)% [gas sensitivity, S (g) = (I (g) - I (a))/I (a) x 100%] and 5.11 x 10(2)% to 100 ppm methanol gas at a temperature of 300A degrees C and 100A degrees C, respectively, has been observed. A fast response time of 200 ms and 270 ms as well as a recovery time of 120 ms and 1330 ms to methanol gas have also been found at an operating temperature of 300A degrees C and 100A degrees C, respectively. The response and recovery time decreases with increasing operation temperature of the sensor.