Thermal decomposition-assisted, aspect ratio controlled ZnO nanorods towards highly selective H2 gas detection

Abstract

ZnO nanostructures with various aspect ratios have been synthesized for H-2 gas detection applications. The thermal-decomposition method was employed at different annealing temperatures (350, 450, and 550 degrees C) and its impact on various shapes/sizes of ZnO nanostructures is demonstrated. Thermal decomposition performed at 350 degrees C exhibited a maximum (similar to 6.25) aspect ratio among them. Its capability of H-2 sensing was also observed to be maximum by realizing similar to 483% of sensor response at 180 degrees C under H-2 gas concentration of 80 ppm. The sensor response is similar to 3 times (similar to 177%) and similar to 9 times (similar to 53%) higher at ZnO nanostructure synthesized at 350 degrees C than at 450 degrees C, and 550 degrees C, respectively. The higher sensor response has been attributed to the increased availability of active surface area for adsorption/desorption of gas molecules. ZnO@350 nanostructure showed significantly higher selectivity towards H-2 gas than other target chemical inputs. We have also studied H-2-induced metallization on the surface of ZnO nanostructures which plays an important role for improving the selectivity and sensor response. This study provides insight into the role of aspect-ratio-controlled shape/sized ZnO in improving H-2 gas sensing.