Effect of reaction time and Sb doping ratios on the architecturing of ZnO nanomaterials for gas sensor applications

- The well-formed ZnO with flower-like nanorod structures has been obtained at 24 h reaction time.
- 24 h is the optimum reaction time to produce ZnO with high degree of crystallinity.
- Antimony doped with any ratio in nanorod ZnO changes the morphological structure into pyramids-like nanoparticles.
- The highest sensitivity was established for acetone vapor for both pure ZnO and Sb doped ZnO gas sensor.
- The maximum acetone sensitivity of 95% was recorded for Sb doped ZnO with ratio 95:5.

ZnO nanostructures including nanorods and nanoparticles were synthesized via sol-gel technique. The factors were optimized in order to acquire undoped and doped ZnO that have nanorod morphological structures with high aspect ratio. Effect of reaction times (3, 6, 12, 24, and 48 h) has been studied to optimize the best preparation conditions. The morphological structure, diameter and length of ZnO nanorods were determined using scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM). Nanoparticles of about 10 nm and nanorods with diameter about 100 nm were measured using (HRTEM). The maximum aspect ratio of nanorods has a value of 12 for 24 h reaction times. X-ray diffraction (XRD) patterns for the as-synthesized ZnO nanopowders reveal a highly crystallized wurtzite structure. XRD also used for identifying phase structure and chemical state of ZnO and ZnO doped with Sb under different reaction times and different doping ratios. Chemical composition of the Sb-doped ZnO nanopowders was performed with energy dispersive X-ray (EDX) and inductive coupled plasma mass spectroscopy (ICP-AES), which also concluded the doping ratios of the reactions results. Effect of doping on the band gap values for ZnO nanopowders has been studied using UV-vis spectroscopy. The gas response of the homemade devices based on Sb-doped ZnO nanopowders toward O2, CO2 and Acetone vapor as a function of temperature was measured and compared with undoped ZnO films. The response and recovery times have been studied.